0000950170-23-059750 | 10-Q | XBRL Viewer

Summary of Significant Accounting Policies	9 Months Ended
Sep. 30, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies The following is a summary of significant accounting policies followed in the preparation of these condensed consolidated financial statements. Basis of Presentation The condensed consolidated financial statements of the Company included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission. Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) have been condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements as of and for the year ended December 31, 2022, included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022. The condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements. In the opinion of the Company’s management, the accompanying condensed consolidated financial statements contain all adjustments, consisting of only normal recurring adjustments, necessary for a fair statement of its financial position as of September 30, 2023, its results of operations and comprehensive loss for the three and nine months ended September 30, 2023 and 2022, its cash flows for the nine months ended September 30, 2023 and 2022, and its statements of changes in stockholders’ equity for the three and nine months ended September 30, 2023 and 2022. The consolidated balance sheet at December 31, 2022 was derived from audited financial statements, but does not include all disclosures required by GAAP. The results for the three and nine months ended September 30, 2023 are not necessarily indicative of the results for the year ending December 31, 2023, or for any future period. Principles of Consolidation The condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries as disclosed in Note 2, Summary of Significant Accounting Policies, within the “Notes to Consolidated Financial Statements” accompanying its Annual Report on Form 10-K for the year ended December 31, 2022. Intercompany accounts and transactions have been eliminated. Use of Estimates The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Research and Development Costs and Accruals Research and development expenses are comprised of costs incurred in performing research and development activities, including salaries and benefits, overhead costs, depreciation, contract services and other related costs. Research and development costs are expensed to operations as the related obligation is incurred. The Company has entered into various research and development contracts with research institutions and other companies both inside and outside of the U.S. These agreements are generally cancelable, and related costs are recorded as research and development expenses as incurred. The Company records accruals for estimated ongoing research and development costs. When billing terms under these contracts do not coincide with the timing of when the work is performed, the Company is required to make estimates of outstanding obligations to those third parties as of the end of the reporting period. Any accrual estimates are based on a number of factors, including the Company’s knowledge of the progress towards completion of the research and development activities, invoicing to date under the contracts, communication from the research institution or other companies of any actual costs incurred during the period that have not yet been invoiced, and the costs included in the contracts. Significant judgments and estimates are made in determining the accrued balances at the end of any reporting period. Actual results could differ from the estimates made by the Company. The historical accrual estimates made by the Company have not been materially different from the actual costs. Revenue Recognition The Company generates revenue from the sale of ZULRESSO, which was approved by the FDA in March 2019 and the Company subsequently began selling in June 2019, and from collaboration and supply agreements with the Company’s collaborators. To date, revenue from collaboration agreements has come from initial, upfront payments allocated to licenses of intellectual property delivered to the Company’s collaborators and from the supply of material for clinical trials under a supply agreement. Under Accounting Standards Codification (“ASC”) Topic 606, Revenue from Contracts with Customers (“Topic 606”), an entity recognizes revenue when or as performance obligations are satisfied by transferring control of promised goods or services to a customer, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of Topic 606, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price, including variable consideration, if any; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. Arrangements that include rights to additional goods or services that are exercisable at a customer’s discretion are generally considered options. The Company assesses if these options provide a material right to the customer and if so, they are considered performance obligations. The exercise of a material right may be accounted for as a contract modification or as a continuation of the contract for accounting purposes. For contracts determined to be within the scope of Topic 606, the Company assesses whether the goods or services promised within each contract are distinct to identify those that are performance obligations. This assessment involves subjective determinations and requires management to make judgments about the individual promised goods or services and whether such are separable from the other aspects of the contractual relationship. Promised goods and services are considered distinct provided that: (i) the customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer and (ii) the entity’s promise to transfer the good or service to the customer is separately identifiable from other promises in the contract. The Company allocates the transaction price (the amount of consideration it expects to be entitled to from a customer in exchange for the promised goods or services) to each performance obligation and recognizes the associated revenue when (or as) each performance obligation is satisfied. The Company’s estimate of the transaction price for each contract includes all variable consideration to which the Company expects to be entitled. Collaboration and License Revenue In assessing whether a promised good or service is distinct in the evaluation of a collaboration or license arrangement subject to Topic 606, the Company considers factors such as the research, manufacturing and commercialization capabilities of the collaboration partner and the availability of the associated expertise in the general marketplace. The Company also considers the intended benefit of the contract in assessing whether a promised good or service is separately identifiable from other promises in the contract. If a promised good or service is not distinct, the Company is required to combine that good or service with other promised goods or services until it identifies a bundle of goods or services that is distinct. The transaction price is then determined and allocated to the identified performance obligations in proportion to their standalone selling prices (“SSP”) on a relative SSP basis. SSP is determined at contract inception and is not updated to reflect changes between contract inception and when the performance obligations are satisfied. Determining the SSP for performance obligations requires significant judgment. In developing the SSP for a performance obligation, the Company considers applicable market conditions and relevant entity-specific factors, including factors that were contemplated in negotiating the agreement with the customer and estimated costs. In certain circumstances, the Company may apply the residual method to determine the SSP of a good or service if the standalone selling price is considered highly variable or uncertain. The Company validates the SSP for performance obligations by evaluating whether changes in the key assumptions used to determine the SSP will have a significant effect on the allocation of arrangement consideration between multiple performance obligations. If the consideration promised in a contract includes a variable amount, the Company estimates the amount of consideration to which it will be entitled in exchange for transferring the promised goods or services to a customer. The Company determines the amount of variable consideration by using the expected value method or the most likely amount method. The Company includes the unconstrained amount of estimated variable consideration in the transaction price. The amount included in the transaction price is constrained to the amount for which it is probable that a significant reversal of cumulative revenue recognized will not occur. At the end of each subsequent reporting period, the Company re-evaluates the estimated variable consideration included in the transaction price and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis in the period of adjustment. If an arrangement includes development and regulatory milestone payments, the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company’s control or the licensee’s control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. In determining the transaction price, the Company adjusts consideration for the effects of the time value of money if the timing of payments provides the Company with a significant benefit of financing. The Company does not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between payment by the licensees and the transfer of the promised goods or services to the licensees will be one year or less. The Company assessed its arrangements with Shionogi and Biogen and concluded that a significant financing component does not exist for either arrangement. For arrangements with licenses of intellectual property that include sales-based royalties or milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties or milestone payments relate, the Company recognizes royalty revenue and sales-based milestones at the later of (i) when the related sales occur, or (ii) when the performance obligation to which the royalty or milestone payment has been allocated has been satisfied. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) each performance obligation is satisfied at a point in time or over time, and if over time this is based on the use of an output or input method. Revenue from the Company’s collaboration agreement with Shionogi has come from initial, upfront consideration upon execution of the agreement and for the supply of drug product for Shionogi’s clinical trials. Revenue from the Company’s collaboration agreement with Biogen has come from initial, upfront consideration related to the execution of the Biogen Collaboration Agreement. For additional information, refer to Note 6, Collaboration Agreements. Product Revenue, Net The Company recognizes product revenue, net of variable consideration related to certain allowances and accruals that are determined using the expected value method, in its condensed consolidated financial statements at the point in time when control transfers to the customer, which is typically when the product has been delivered to the customer’s location. The amount included in the transaction price is constrained to the amount for which it is probable that a significant reversal of cumulative revenue recognized will not occur. The Company’s only performance obligation identified for ZULRESSO is to deliver the product to the location specified by the customer’s order. The Company records shipping and handling costs associated with delivery of product to its customers within selling, general and administrative expenses on its condensed consolidated statements of operations and comprehensive loss. The Company expenses incremental costs of obtaining a contract as incurred if the expected amortization period of the asset would be less than one year. If the Company were to incur incremental costs with an amortization period greater than a year, such costs would be capitalized as contract assets, as they are expected to be recovered, and would be expensed by amortizing on a systematic basis that is consistent with the transfer to the customer of the goods or services to which the asset relates. The Company did not have any contract assets (unbilled receivables) at September 30, 2023, as customer invoicing generally occurs before or at the time of revenue recognition. The Company did not have any contract liabilities at September 30, 2023 related to its sales of ZULRESSO, as the Company did not receive any payments in advance of satisfying its performance obligations to its customers. Amounts billed or invoiced that are considered trade accounts receivable are included in prepaid expenses and other current assets on the condensed consolidated balance sheets. As of September 30, 2023 and December 31, 2022, the Company had not provided any allowance for bad debts against the trade accounts receivable, and the amount of trade accounts receivable was not significant. The Company records reserves, based on contractual terms, for the following components of variable consideration related to product sold during the reporting period, as well as its estimate of product that remains in the distribution channel inventory of its customers at the end of the reporting period. On a quarterly basis, the Company updates its estimates, if necessary, and records any material adjustments in the period they are identified. Chargebacks: The Company estimates chargebacks from its customers who directly purchase the product from the Company for discounts resulting from contractual commitments to sell products to eligible healthcare settings at prices lower than the list prices charged to its customers. Customers charge the Company for the difference between what they pay to the Company for the product and the selling price to the eligible healthcare settings. Reserves for chargebacks consist of credits that the Company expects to issue for units that remain in the distribution channel inventories at the end of each reporting period that the Company expects will be sold to eligible healthcare settings, and chargebacks that customers have claimed, but for which the Company has not yet issued a credit. Government Rebates: The Company is subject to discount obligations under government programs, including Medicaid. The Company records reserves for rebates in the same period the related product revenue is recognized, resulting in a reduction of ZULRESSO product revenue and a current liability that is included in accrued expenses on its condensed consolidated balance sheets. The Company’s liability for these rebates consists of invoices received for claims from prior quarters that have not been paid or for which an invoice has not yet been received, estimates of claims for the current quarter, and estimates of future claims that will be made for product that has been recognized as revenue, but which remains in the distribution channel at the end of each reporting period. Trade Discounts and Allowances: The Company generally provides customary invoice discounts on ZULRESSO sales to its customers for prompt payment and the Company pays fees for sales order management, data, and distribution services. The Company estimates its customers will earn these discounts and fees and deducts these discounts and fees in full from gross ZULRESSO revenue and accounts receivable at the time the Company recognizes the related revenue. Financial Assistance: The Company provides voluntary financial assistance programs to patients with commercial insurance that have coverage and reside in states that allow financial assistance. The Company estimates the financial assistance amounts for ZULRESSO and records any such amounts within accrued expenses on its condensed consolidated balance sheets. The calculation of the accrual for financial assistance is based on an estimate of claims and the cost per claim that the Company expects to receive using demographics for patients who have registered and been approved for assistance. Any adjustments are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability, which is included as a component of accrued expenses on the condensed consolidated balance sheets. Product Returns: Consistent with industry practice, the Company offers product return rights to customers for damaged, defective or expiring product, provided it is within a specified period around the product expiration date as set forth in the Company’s return goods policy. The Company estimates the amount of its product sales that may be returned by its customers and records this estimate as a reduction of revenue in the period the related product revenue is recognized, as well as a reserve within accrued expenses on the condensed consolidated balance sheets. Product returns have not been significant to date and are not expected to be significant in the future. Collaborative Arrangements The Company analyzes its collaboration arrangements to assess whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities and therefore within the scope of ASC Topic 808, Collaborative Arrangements (“Topic 808”). This assessment is performed throughout the life of the arrangement based on changes in the responsibilities of all parties in the arrangement. For collaboration arrangements within the scope of Topic 808 that contain multiple elements, the Company first determines which elements of the collaboration are deemed to be within the scope of Topic 808 and which elements of the collaboration are more reflective of a vendor-customer relationship and therefore within the scope of Topic 606. For elements of collaboration arrangements that are accounted for pursuant to Topic 808, an appropriate recognition method is determined and applied consistently, either by analogy to authoritative accounting literature or by applying a reasonable and rational policy election. For those elements of the arrangement that are accounted for pursuant to Topic 606, the Company applies the five-step model described above, and presents the arrangement as collaboration revenue in the condensed consolidated statements of operations and comprehensive loss. For collaboration arrangements that are within the scope of Topic 808, the Company evaluates the income statement classification for presentation of amounts due from or owed to other participants associated with multiple activities in a collaboration arrangement based on the nature of each separate activity. Payments or reimbursements that are the result of a collaborative relationship instead of a customer relationship, such as co-development and co-commercialization activities, are recorded as research and development expense or selling, general and administrative expense, in the event of a payment to the collaborative partner in a period, or a reduction to these expense line items in the event of a reimbursement from the collaboration partner in a period, as appropriate. Fair Value Measurements Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Financial assets and liabilities carried at fair value are classified and disclosed in one of the following three categories: Level 1 — Quoted market prices in active markets for identical assets or liabilities. Level 2 — Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The Company’s cash equivalents and marketable securities at September 30, 2023 and December 31, 2022 were carried at fair value, determined according to the fair value hierarchy; see Note 3, Fair Value Measurements. The carrying amounts reflected in the condensed consolidated balance sheets for the collaboration receivable – related party, accounts payable and accrued expenses approximate their fair values due to their short-term maturities at September 30, 2023 and December 31, 2022, respectively. Recently Issued Accounting Pronouncements Accounting standards that have been issued or proposed by the Financial Accounting Standards Board or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s condensed consolidated financial statements upon adoption.

Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2023

Summary of Significant Accounting Policies

The following is a summary of significant accounting policies followed in the preparation of these condensed consolidated financial statements.

Basis of Presentation

The condensed consolidated financial statements of the Company included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission. Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) have been condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these condensed consolidated financial statements should be read in conjunction with the

audited consolidated financial statements as of and for the year ended December 31, 2022, included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022.

The condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements. In the opinion of the Company’s management, the accompanying condensed consolidated financial statements contain all adjustments, consisting of only normal recurring adjustments, necessary for a fair statement of its financial position as of September 30, 2023, its results of operations and comprehensive loss for the three and nine months ended September 30, 2023 and 2022, its cash flows for the nine months ended September 30, 2023 and 2022, and its statements of changes in stockholders’ equity for the three and nine months ended September 30, 2023 and 2022. The consolidated balance sheet at December 31, 2022 was derived from audited financial statements, but does not include all disclosures required by GAAP. The results for the three and nine months ended September 30, 2023 are not necessarily indicative of the results for the year ending December 31, 2023, or for any future period.

Principles of Consolidation

The condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries as disclosed in Note 2, Summary of Significant Accounting Policies, within the “Notes to Consolidated Financial Statements” accompanying its Annual Report on Form 10-K for the year ended December 31, 2022. Intercompany accounts and transactions have been eliminated.

Use of Estimates

The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting period.

Research and Development Costs and Accruals

Research and development expenses are comprised of costs incurred in performing research and development activities, including salaries and benefits, overhead costs, depreciation, contract services and other related costs. Research and development costs are expensed to operations as the related obligation is incurred.

The Company has entered into various research and development contracts with research institutions and other companies both inside and outside of the U.S. These agreements are generally cancelable, and related costs are recorded as research and development expenses as incurred. The Company records accruals for estimated ongoing research and development costs. When billing terms under these contracts do not coincide with the timing of when the work is performed, the Company is required to make estimates of outstanding obligations to those third parties as of the end of the reporting period. Any accrual estimates are based on a number of factors, including the Company’s knowledge of the progress towards completion of the research and development activities, invoicing to date under the contracts, communication from the research institution or other companies of any actual costs incurred during the period that have not yet been invoiced, and the costs included in the contracts. Significant judgments and estimates are made in determining the accrued balances at the end of any reporting period. Actual results could differ from the estimates made by the Company. The historical accrual estimates made by the Company have not been materially different from the actual costs.

Revenue Recognition

The Company generates revenue from the sale of ZULRESSO, which was approved by the FDA in March 2019 and the Company subsequently began selling in June 2019, and from collaboration and supply agreements with the Company’s collaborators. To date, revenue from collaboration agreements has come from initial, upfront payments allocated to licenses of intellectual property delivered to the Company’s collaborators and from the supply of material for clinical trials under a supply agreement.

Under Accounting Standards Codification (“ASC”) Topic 606, Revenue from Contracts with Customers (“Topic 606”), an entity recognizes revenue when or as performance obligations are satisfied by transferring control of promised goods or services to a customer, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of Topic 606, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price, including variable consideration, if any; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. Arrangements that include rights to additional goods or services that are exercisable at a customer’s discretion are generally considered options. The Company assesses if these options provide a material right to the customer and if so, they are considered performance obligations. The exercise of a material right may be accounted for as a contract modification or as a continuation of the contract for accounting purposes.

For contracts determined to be within the scope of Topic 606, the Company assesses whether the goods or services promised within each contract are distinct to identify those that are performance obligations. This assessment involves subjective determinations and requires management to make judgments about the individual promised goods or services and whether such are separable from the other aspects of the contractual relationship. Promised goods and services are considered distinct provided that: (i) the customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer and (ii) the entity’s promise to transfer the good or service to the customer is separately identifiable from other promises in the contract.

The Company allocates the transaction price (the amount of consideration it expects to be entitled to from a customer in exchange for the promised goods or services) to each performance obligation and recognizes the associated revenue when (or as) each performance obligation is satisfied. The Company’s estimate of the transaction price for each contract includes all variable consideration to which the Company expects to be entitled.

Collaboration and License Revenue

In assessing whether a promised good or service is distinct in the evaluation of a collaboration or license arrangement subject to Topic 606, the Company considers factors such as the research, manufacturing and commercialization capabilities of the collaboration partner and the availability of the associated expertise in the general marketplace. The Company also considers the intended benefit of the contract in assessing whether a promised good or service is separately identifiable from other promises in the contract. If a promised good or service is not distinct, the Company is required to combine that good or service with other promised goods or services until it identifies a bundle of goods or services that is distinct.

The transaction price is then determined and allocated to the identified performance obligations in proportion to their standalone selling prices (“SSP”) on a relative SSP basis. SSP is determined at contract inception and is not updated to reflect changes between contract inception and when the performance obligations are satisfied. Determining the SSP for performance obligations requires significant judgment. In developing the SSP for a performance obligation, the Company considers applicable market conditions and relevant entity-specific factors, including factors that were contemplated in negotiating the agreement with the customer and estimated costs. In certain circumstances, the Company may apply the residual method to determine the SSP of a good or service if the standalone selling price is considered highly variable or uncertain. The Company validates the SSP for performance obligations by evaluating whether changes in the key assumptions used to determine the SSP will have a significant effect on the allocation of arrangement consideration between multiple performance obligations.

If the consideration promised in a contract includes a variable amount, the Company estimates the amount of consideration to which it will be entitled in exchange for transferring the promised goods or services to a customer. The Company determines the amount of variable consideration by using the expected value method or the most likely amount method. The Company includes the unconstrained amount of estimated variable consideration in the transaction price. The amount included in the transaction price is constrained to the amount for which it is probable that a significant reversal of cumulative revenue recognized will not occur. At the end of each subsequent reporting period, the Company re-evaluates the estimated variable consideration included in the transaction price and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis in the period of adjustment.

If an arrangement includes development and regulatory milestone payments, the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company’s control or the licensee’s control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received.

In determining the transaction price, the Company adjusts consideration for the effects of the time value of money if the timing of payments provides the Company with a significant benefit of financing. The Company does not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between payment by the licensees and the transfer of the promised goods or services to the licensees will be one year or less. The Company assessed its arrangements with Shionogi and Biogen and concluded that a significant financing component does not exist for either arrangement. For arrangements with licenses of intellectual property that include sales-based royalties or milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties or milestone payments relate, the Company recognizes royalty revenue and sales-based milestones at the later of (i) when the related sales occur, or (ii) when the performance obligation to which the royalty or milestone payment has been allocated has been satisfied.

The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) each performance obligation is satisfied at a point in time or over time, and if over time this is based on the use of an output or input method. Revenue from the Company’s collaboration agreement with Shionogi has come from initial, upfront consideration upon execution of the agreement and for the supply of drug product for Shionogi’s clinical trials. Revenue from the Company’s collaboration agreement with Biogen has come from initial, upfront consideration related to the execution of the Biogen Collaboration Agreement. For additional information, refer to Note 6, Collaboration Agreements.

Product Revenue, Net

The Company recognizes product revenue, net of variable consideration related to certain allowances and accruals that are determined using the expected value method, in its condensed consolidated financial statements at the point in time when control transfers to the customer, which is typically when the product has been delivered to the customer’s location. The amount included in the transaction price is constrained to the amount for which it is probable that a significant reversal of cumulative revenue recognized will not occur. The Company’s only performance obligation identified for ZULRESSO is to deliver the product to the location specified by the customer’s order. The Company records shipping and handling costs associated with delivery of product to its customers within selling, general and administrative expenses on its condensed consolidated statements of operations and comprehensive loss. The Company expenses incremental costs of obtaining a contract as incurred if the expected amortization period of the asset would be less than one year. If the Company were to incur incremental costs with an amortization period greater than a year, such costs would be capitalized as contract assets, as they are expected to be recovered, and would be expensed by amortizing on a systematic basis that is consistent with the transfer to the customer of the goods or services to which the asset relates. The Company did not have any contract assets (unbilled receivables) at September 30, 2023, as customer invoicing generally occurs before or at the time of revenue recognition. The Company did not have any contract liabilities at September 30, 2023 related to its sales of ZULRESSO, as the Company did not receive any payments in advance of satisfying its performance obligations to its customers. Amounts billed or invoiced that are considered trade accounts receivable are included in prepaid expenses and other current assets on the condensed consolidated balance sheets.

As of September 30, 2023 and December 31, 2022, the Company had not provided any allowance for bad debts against the trade accounts receivable, and the amount of trade accounts receivable was not significant.

The Company records reserves, based on contractual terms, for the following components of variable consideration related to product sold during the reporting period, as well as its estimate of product that remains in the distribution channel inventory of its customers at the end of the reporting period. On a quarterly basis, the Company updates its estimates, if necessary, and records any material adjustments in the period they are identified.

Chargebacks: The Company estimates chargebacks from its customers who directly purchase the product from the Company for discounts resulting from contractual commitments to sell products to eligible healthcare settings at prices lower than the list prices charged to its customers. Customers charge the Company for the difference between what they pay to the Company for the product and the selling price to the eligible healthcare settings. Reserves for chargebacks consist of credits that the Company expects to issue for units that remain in the distribution channel inventories at the end of each reporting period that the Company expects will be sold to eligible healthcare settings, and chargebacks that customers have claimed, but for which the Company has not yet issued a credit.

Government Rebates: The Company is subject to discount obligations under government programs, including Medicaid. The Company records reserves for rebates in the same period the related product revenue is recognized, resulting in a reduction of ZULRESSO product revenue and a current liability that is included in accrued expenses on its condensed consolidated balance sheets. The Company’s liability for these rebates consists of invoices received for claims from prior quarters that have not been paid or for which an invoice has not yet been received, estimates of claims for the current quarter, and estimates of future claims that will be made for product that has been recognized as revenue, but which remains in the distribution channel at the end of each reporting period.

Trade Discounts and Allowances: The Company generally provides customary invoice discounts on ZULRESSO sales to its customers for prompt payment and the Company pays fees for sales order management, data, and distribution services. The Company estimates its customers will earn these discounts and fees and deducts these discounts and fees in full from gross ZULRESSO revenue and accounts receivable at the time the Company recognizes the related revenue.

Financial Assistance: The Company provides voluntary financial assistance programs to patients with commercial insurance that have coverage and reside in states that allow financial assistance. The Company estimates the financial assistance amounts for ZULRESSO and records any such amounts within accrued expenses on its condensed consolidated balance sheets. The calculation of the accrual for financial assistance is based on an estimate of claims and the cost per claim that the Company expects to receive using demographics for patients who have registered and been approved for assistance. Any adjustments are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability, which is included as a component of accrued expenses on the condensed consolidated balance sheets.

Product Returns: Consistent with industry practice, the Company offers product return rights to customers for damaged, defective or expiring product, provided it is within a specified period around the product expiration date as set forth in the Company’s return goods policy. The Company estimates the amount of its product sales that may be returned by its customers and records this estimate as a reduction of revenue in the period the related product revenue is recognized, as well as a reserve within accrued expenses on the condensed consolidated balance sheets. Product returns have not been significant to date and are not expected to be significant in the future.

Collaborative Arrangements

The Company analyzes its collaboration arrangements to assess whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities and therefore within the scope of ASC Topic 808, Collaborative Arrangements (“Topic 808”). This assessment is performed throughout the life of the arrangement based on changes in the responsibilities of all parties in the arrangement. For collaboration arrangements within the scope of Topic 808 that contain multiple elements, the Company first determines which elements of the collaboration are deemed to be

within the scope of Topic 808 and which elements of the collaboration are more reflective of a vendor-customer relationship and therefore within the scope of Topic 606. For elements of collaboration arrangements that are accounted for pursuant to Topic 808, an appropriate recognition method is determined and applied consistently, either by analogy to authoritative accounting literature or by applying a reasonable and rational policy election. For those elements of the arrangement that are accounted for pursuant to Topic 606, the Company applies the five-step model described above, and presents the arrangement as collaboration revenue in the condensed consolidated statements of operations and comprehensive loss.

For collaboration arrangements that are within the scope of Topic 808, the Company evaluates the income statement classification for presentation of amounts due from or owed to other participants associated with multiple activities in a collaboration arrangement based on the nature of each separate activity. Payments or reimbursements that are the result of a collaborative relationship instead of a customer relationship, such as co-development and co-commercialization activities, are recorded as research and development expense or selling, general and administrative expense, in the event of a payment to the collaborative partner in a period, or a reduction to these expense line items in the event of a reimbursement from the collaboration partner in a period, as appropriate.

Fair Value Measurements

Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Financial assets and liabilities carried at fair value are classified and disclosed in one of the following three categories:

Level 1 — Quoted market prices in active markets for identical assets or liabilities.

Level 2 — Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

The Company’s cash equivalents and marketable securities at September 30, 2023 and December 31, 2022 were carried at fair value, determined according to the fair value hierarchy; see Note 3, Fair Value Measurements.

The carrying amounts reflected in the condensed consolidated balance sheets for the collaboration receivable – related party, accounts payable and accrued expenses approximate their fair values due to their short-term maturities at September 30, 2023 and December 31, 2022, respectively.

Recently Issued Accounting Pronouncements

Accounting standards that have been issued or proposed by the Financial Accounting Standards Board or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s condensed consolidated financial statements upon adoption.

Stock-Based Compensation - Additional Information (Detail)			1 Months Ended	3 Months Ended						6 Months Ended	9 Months Ended		12 Months Ended
	Jun. 15, 2023 shares	Jan. 01, 2023 shares	Sep. 30, 2022	Sep. 30, 2023 USD ($) Milestone shares	Jun. 30, 2023 USD ($) shares	Mar. 31, 2023 USD ($) Milestone shares	Sep. 30, 2022 USD ($) shares	Jun. 30, 2022 USD ($) shares	Mar. 31, 2022 shares	Jun. 30, 2023 USD ($) Milestone	Sep. 30, 2023 USD ($) $ / shares shares	Sep. 30, 2022 USD ($) Milestone $ / shares shares	Dec. 31, 2022 shares	Dec. 31, 2021 USD ($) shares	Dec. 31, 2020 shares	Jun. 16, 2022 shares	Sep. 20, 2018 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation granted under plan vested period											4 years
Share based compensation, vest period											1 year
Share based compensation, term of plan											10 years
Total number of shares outstanding				11,420,766							11,420,766
Common stock available for issuance under stock option plan				7,283,210							7,283,210
Restricted stock units granted											2,594,486
Stock-based compensation expense \| $				$ 28,691,000			$ 13,169,000				$ 60,422,000	$ 46,358,000
Outstanding and unvested restricted stock units				3,288,804							3,288,804		1,415,481
Total unrecognized stock-based compensation expense \| $				$ 48,900,000							$ 48,900,000
Weighted average grant date fair value per share \| $ / shares											$ 30.27	$ 25.96
Time Based Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation granted under plan vested period						4 years								4 years	2 years
Share based compensation remaining vesting period						3 years								3 years
Share based compensation vesting frequency														quarterly
Restricted stock units granted				1,382,300	0	330,617						0		268,119	550,890
Restricted stock units vesting period month and year				2025-02
Restricted stock units vested				12,385			59,950	291,505	0		40,962			113,941
Fair value of restricted stock units vested \| $				$ 200,000			$ 2,300,000	$ 9,500,000			$ 1,600,000			$ 8,800,000
Outstanding and unvested restricted stock units				1,721,304							1,721,304
Total unrecognized stock-based compensation expense \| $				$ 42,000,000							$ 42,000,000
Performance Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units granted				19,248			57,480				881,569	569,410
Fair value of restricted stock units vested \| $					$ 0							$ 0
Stock-based compensation expense \| $				$ 2,700,000
Outstanding and unvested restricted stock units				1,567,500							1,567,500
Total unrecognized stock-based compensation expense \| $				$ 71,600,000							$ 71,600,000
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted											919,751
Total number of shares outstanding				8,131,962							8,131,962		7,788,350
Stock-based compensation expense \| $				$ 20,251,000			$ 11,992,000				$ 39,929,000	40,659,000
Weighted average period of unrecognized compensation costs											2 years 9 months
Intrinsic value of options exercised \| $											$ 1,900,000	4,400,000
Performance-Based Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense \| $										$ 0	$ 0	$ 0
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted											0	0
Total unrecognized stock-based compensation expense \| $				$ 24,900,000							$ 24,900,000
Number of shares outstanding and unvested stock options				455,000							455,000
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense \| $				$ 8,101,000			$ 730,000				$ 19,272,000	$ 4,982,000
Restricted Stock Units Vest One Year Anniversary [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units vesting percentage											25.00%
Restricted Stock Units Vest One Year Anniversary [Member] \| Time Based Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units vesting percentage			25.00%			25.00%									25.00%
Restricted stock units vesting period month and year															2021-04
Restricted Stock Units Vest Two Year Anniversary [Member] \| Time Based Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units vesting percentage						75.00%								75.00%	75.00%
Restricted stock units vesting period month and year															2022-04
2011 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted											0
2014 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares annual increase added to plan		2,380,365
2014 Plan [Member] \| Performance Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of restricted stock units vested \| $				2,600,000		$ 5,500,000
Stock-based compensation expense \| $				$ 2,900,000		$ 8,500,000
Regulatory development Milestone achieved \| Milestone				1		1
Number of commercial milestone not met \| Milestone				1
2014 Plan [Member] \| Performance Restricted Stock Units [Member] \| Milestone One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Milestone performance restricted stock percentage						0.27
2014 Plan [Member] \| Performance-Based Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Milestone performance-based stock option grants percentage														30.00%
Stock-based compensation expense \| $				$ 10,700,000
Regulatory development Milestone achieved \| Milestone				1						0		0
2014 Plan [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of increase on outstanding shares of Common stock													4.00%
2016 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total number of shares reserved for issuance																	1,200,000
2014 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional number of shares reserved for issuance	500,000
Total number of shares reserved for issuance	1,082,000															300,000

Accrued Expenses

9 Months Ended

Sep. 30, 2023

Payables and Accruals [Abstract]

Accrued Expenses

The following table summarizes accrued expenses as of September 30, 2023 and December 31, 2022:


	September 30,		December 31,
	2023		2022
	(in thousands)
Accrued research and development costs	$	63,386	$	32,565
Restructuring		24,250		—
Employee-related		14,108		29,372
Professional services		12,497		10,172
Other		660		557
	$	114,901	$	72,666

As of September 30, 2023, accrued research and development costs includes $28.9 million of expenses related to cancelling excess purchase commitments for manufacturing as a result of the CRL received from the FDA for zuranolone for the treatment of MDD. During the three and nine months ended September 30, 2023, the expenses were recorded as research and development expense in the condensed consolidated statements of operations and comprehensive loss, net of amounts subject to reimbursement under the Biogen Collaboration Agreement.

Nature of the Business

9 Months Ended

Sep. 30, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Nature of the Business

Sage Therapeutics, Inc. (“Sage” or the “Company”) is a biopharmaceutical company with a mission to pioneer solutions to deliver life-changing brain health medicines, so every person can thrive.

The Company’s product ZURZUVAE™ (zuranolone) was approved by the U.S. Food and Drug Administration (the “FDA”) on August 4, 2023 for the treatment of postpartum depression (“PPD”) in adults. ZURZUVAE is a neuroactive steroid that is a positive allosteric modulator of GABAA receptors, targeting both synaptic and extrasynaptic GABAA receptors, and is the first oral, once-daily, 14-day treatment specifically indicated for adults with PPD. ZURZUVAE is expected to be commercially available for women with PPD in December 2023 with the broader complement of commercialization capabilities expected to roll out in early 2024. The Company’s product ZULRESSO® (brexanolone) CIV injection is approved in the U.S. for the treatment of PPD in adults. The Company launched ZULRESSO commercially in the U.S. in June 2019. ZULRESSO may only be administered in qualified, medically-supervised healthcare settings. Brexanolone is chemically identical to allopregnanolone, a naturally occurring neuroactive steroid that, like zuranolone, acts as a positive allosteric modulator of GABAA receptors.

Additionally, the FDA issued a complete response letter (“CRL”) related to the Company’s new drug application (“NDA”) for zuranolone for the treatment of major depressive disorder (“MDD”). The CRL stated that the NDA did not provide substantial evidence of effectiveness to support the approval of zuranolone for the treatment of MDD and that one or more additional clinical trials will be needed. The Company and Biogen MA Inc. (“BIMA”) and Biogen International GmbH (collectively with BIMA, “Biogen”) are continuing to review the feedback from the FDA and are evaluating next steps.

The Company has a portfolio of other product candidates with a current focus on modulating two critical central nervous system (“CNS”) receptor systems, GABA and NMDA. The GABA receptor family, which is recognized as the major inhibitory neurotransmitter in the CNS, mediates downstream neurologic and bodily function via activation of GABAA receptors. The NMDA-type receptors of the glutamate receptor system are a major excitatory receptor system in the CNS. Dysfunction in these systems is implicated in a broad range of CNS disorders. The Company is currently targeting diseases and disorders of the brain with three key focus areas: depression, neurology and neuropsychiatry.

The Company was incorporated under the laws of the State of Delaware on April 16, 2010, and commenced operations on January 19, 2011 as Sterogen Biopharma, Inc. On September 13, 2011, the Company changed its name to Sage Therapeutics, Inc.

Risks and Uncertainties

The Company is subject to risks and uncertainties common to companies in the biopharmaceutical industry, including, but not limited to, the risks associated with developing product candidates at each stage of non-clinical and clinical development; the challenges associated with gaining regulatory approval of such product candidates; the risks associated with the marketing and sale of pharmaceutical products; the potential for development by third parties of new technological innovations that may compete with the Company’s products and product candidates; the dependence on key personnel; the challenges of protecting proprietary technology; the need to comply with government regulations; the high costs of drug development; the uncertainty of being able to secure additional capital when needed to fund operations; and the direct or indirect impacts of the macroeconomic environment and geopolitical events on its development activities, operations and financial condition.

The product candidates developed by the Company require approvals from the FDA or foreign regulatory agencies prior to commercial sales. There can be no assurance that the current and future product candidates of the Company will receive, or that the Company’s current products, ZULRESSO and ZURZUVAE, will maintain, the necessary approvals. If

the Company fails to successfully complete clinical development and generate results sufficient to file for regulatory approval or is denied approval or approval is delayed for any of its product candidates, such occurrences may have a material adverse impact on the Company’s business and its financial condition.

The Company is also subject to additional risks and uncertainties arising from changes to the macroeconomic environment and geopolitical events. U.S. and global financial markets have experienced volatility and disruption due to macroeconomic and geopolitical events such as rising inflation, the risk of a recession and ongoing conflicts in other countries. In addition, if equity and credit markets deteriorate, including as a result of past and potential future bank failures, it may make any future debt or equity financing more difficult to obtain on favorable terms, and potentially more dilutive to its existing stockholders. The Company cannot predict at this time to what extent it and its collaborators, employees, suppliers, contract manufacturers and/or vendors could potentially be negatively impacted by these events.

Going Concern

Under Accounting Standards Update (“ASU”) No. 2014-15, Presentation of Financial Statements—Going Concern (Subtopic 205-40), the Company has the responsibility to evaluate whether conditions and/or events raise substantial doubt about its ability to meet its future financial obligations as they become due within one year after the date that the financial statements are issued. The Company has incurred losses and negative cash flows from operations in each year since its inception, except for net income of $606.1 million for the year ended December 31, 2020, reflecting revenue recognized under a collaboration and license agreement with Biogen (the “Biogen Collaboration Agreement”). As of September 30, 2023, the Company had an accumulated deficit of $2.5 billion. From its inception through September 30, 2023, the Company has received aggregate net proceeds of $2.8 billion from the sales of redeemable convertible preferred stock prior to its initial public offering (“IPO”), the issuance of convertible notes, and the sales of common stock in its IPO in July 2014, in follow-on public offerings, and to BIMA under a stock purchase agreement executed in connection with the Biogen Collaboration Agreement. The Company has also received $1.0 billion in upfront payments under its collaborations with Biogen and Shionogi & Co., Ltd. (“Shionogi”). Until such time, if ever, as the Company can generate substantial product revenue and/or collaboration revenue and achieve sustained profitability, the Company expects to finance its cash needs through a combination of equity offerings, debt financings, collaborations, strategic alliances, licensing arrangements and other sources of funding. If the Company is unable to raise additional funds through equity or debt financings or other sources of funding when needed, the Company may be required to delay, limit, reduce or terminate product development or future commercialization efforts or grant rights to develop and market products or product candidates that the Company would otherwise prefer to develop and market itself.

The Company expects that, based on its current operating plans, the Company’s existing cash, cash equivalents and marketable securities will be sufficient to fund its currently planned operations for at least the next 12 months from the filing date of these unaudited interim condensed consolidated financial statements (“condensed consolidated financial statements”). At some point after that time, the Company anticipates it will require additional financing to fund its future operations. Even if the Company believes it has sufficient funds for its current or future operating plans, the Company may seek to raise additional capital if market conditions are favorable or in light of other strategic considerations.

Stock-Based Compensation - Summary of Activity Relating to Time Based and Performance Based Stock Options (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ending balance, Outstanding Shares	11,420,766
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance, Outstanding Shares	7,788,350
Granted, Shares	919,751
Exercised, Shares	(65,940)
Forfeited, Shares	(510,199)
Ending balance, Outstanding Shares	8,131,962	7,788,350
Exercisable, Shares	5,934,180
Beginning balance, Outstanding Weighted Average Exercise Price	$ 77.95
Granted, Weighted Average Exercise Price	45.76
Exercised, Weighted Average Exercise Price	16.58
Forfeited, Weighted Average Exercise Price	56.31
Ending balance, Outstanding Weighted Average Exercise Price	76.17	$ 77.95
Exercisable, Weighted Average Exercise Price	$ 82.73
Outstanding, Weighted Average Remaining Life	5 years 10 months 28 days	6 years 4 months 9 days
Exercisable, Weighted Average Remaining Life	5 years
Outstanding, Aggregate Intrinsic Value	$ 371	$ 7,275
Exercisable, Aggregate Intrinsic Value	$ 370

Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
Balances at Dec. 31, 2021	$ 1,729,031	$ 6	$ (400)	$ 3,227,471	$ (2,660)	$ (1,495,386)
Balances, Shares at Dec. 31, 2021		58,937,050	3,033
Issuance of common stock from exercises of stock options, Amount	646			646
Issuance of common stock from exercises of stock options, Shares		105,474
Issuance of common stock under the employee stock purchase plan	1,153			1,153
Issuance of common stock under the employee stock purchase plan, Shares		23,625
Stock-based compensation expense	18,268			18,268
Change in unrealized loss on available-for-sale securities	(8,541)				(8,541)
Net loss	(122,055)					(122,055)
Balances at Mar. 31, 2022	1,618,502	$ 6	$ (400)	3,247,538	(11,201)	(1,617,441)
Balance, Shares at Mar. 31, 2022		59,066,149	3,033
Balances at Dec. 31, 2021	1,729,031	$ 6	$ (400)	3,227,471	(2,660)	(1,495,386)
Balances, Shares at Dec. 31, 2021		58,937,050	3,033
Net loss	(385,638)
Balances at Sep. 30, 2022	1,380,122	$ 6	$ (400)	3,276,423	(14,883)	(1,881,024)
Balance, Shares at Sep. 30, 2022		59,493,704	3,033
Balances at Mar. 31, 2022	1,618,502	$ 6	$ (400)	3,247,538	(11,201)	(1,617,441)
Balances, Shares at Mar. 31, 2022		59,066,149	3,033
Issuance of common stock from exercises of stock options, Amount	37			37
Issuance of common stock from exercises of stock options, Shares		31,801
Stock-based compensation expense	14,652			14,652
Change in unrealized loss on available-for-sale securities	(2,671)				(2,671)
Vesting of restricted stock units, net of employee tax obligations	(24)			(24)
Vesting of restricted stock units, net of employee tax obligations, Shares		290,779
Net loss	(126,260)					(126,260)
Balances at Jun. 30, 2022	1,504,236	$ 6	$ (400)	3,262,203	(13,872)	(1,743,701)
Balance, Shares at Jun. 30, 2022		59,388,729	3,033
Issuance of common stock from exercises of stock options, Amount	320			320
Issuance of common stock from exercises of stock options, Shares		11,808
Issuance of common stock under the employee stock purchase plan	1,193			1,193
Issuance of common stock under the employee stock purchase plan, Shares		33,614
Stock-based compensation expense	12,722			12,722
Change in unrealized loss on available-for-sale securities	(1,011)				(1,011)
Vesting of restricted stock units, net of employee tax obligations	(15)			(15)
Vesting of restricted stock units, net of employee tax obligations, Shares		59,553
Net loss	(137,323)					(137,323)
Balances at Sep. 30, 2022	1,380,122	$ 6	$ (400)	3,276,423	(14,883)	(1,881,024)
Balance, Shares at Sep. 30, 2022		59,493,704	3,033
Balances at Dec. 31, 2022	1,252,599	$ 6	$ (400)	3,291,369	(10,206)	(2,028,170)
Balances, Shares at Dec. 31, 2022		59,509,125	3,033
Issuance of common stock from exercises of stock options, Amount	438			438
Issuance of common stock from exercises of stock options, Shares		52,058
Issuance of common stock under the employee stock purchase plan	2,863			2,863
Issuance of common stock under the employee stock purchase plan, Shares		76,105
Stock-based compensation expense	19,568			19,568
Change in unrealized loss on available-for-sale securities	5,118				5,118
Vesting of restricted stock units, net of employee tax obligations	(629)			(629)
Vesting of restricted stock units, net of employee tax obligations, Shares		124,713
Net loss	(146,828)					(146,828)
Balances at Mar. 31, 2023	(1,133,129)	$ 6	$ (400)	3,313,609	(5,088)	(2,174,998)
Balance, Shares at Mar. 31, 2023		59,762,001	3,033
Balances at Dec. 31, 2022	1,252,599	$ 6	$ (400)	3,291,369	(10,206)	(2,028,170)
Balances, Shares at Dec. 31, 2022		59,509,125	3,033
Net loss	(508,783)
Balances at Sep. 30, 2023	816,659	$ 6	$ (400)	3,357,741	(3,735)	(2,536,953)
Balance, Shares at Sep. 30, 2023		59,967,516	3,033
Balances at Mar. 31, 2023	(1,133,129)	$ 6	$ (400)	3,313,609	(5,088)	(2,174,998)
Balances, Shares at Mar. 31, 2023		59,762,001	3,033
Issuance of common stock from exercises of stock options, Amount	855			855
Issuance of common stock from exercises of stock options, Shares		20,032
Stock-based compensation expense	11,281			11,281
Change in unrealized loss on available-for-sale securities	(556)				(556)
Vesting of restricted stock units, net of employee tax obligations	(8)			(8)
Vesting of restricted stock units, net of employee tax obligations, Shares		13,972
Net loss	(160,325)					(160,325)
Balances at Jun. 30, 2023	984,376	$ 6	$ (400)	3,325,737	(5,644)	(2,335,323)
Balance, Shares at Jun. 30, 2023		59,796,005	3,033
Issuance of common stock under the employee stock purchase plan	3,656			3,656
Issuance of common stock under the employee stock purchase plan, Shares		87,938
Stock-based compensation expense	28,352			28,352
Change in unrealized loss on available-for-sale securities	1,909				1,909
Vesting of restricted stock units, net of employee tax obligations	(4)			(4)
Vesting of restricted stock units, net of employee tax obligations, Shares		83,573
Net loss	(201,630)					(201,630)
Balances at Sep. 30, 2023	$ 816,659	$ 6	$ (400)	$ 3,357,741	$ (3,735)	$ (2,536,953)
Balance, Shares at Sep. 30, 2023		59,967,516	3,033

Fair Value Measurements

9 Months Ended

Sep. 30, 2023

Fair Value Disclosures [Abstract]

Fair Value Measurements

The Company’s cash equivalents are classified within Level 1 and Level 2 of the fair value hierarchy. The Company’s investments in marketable securities are classified within Level 2 of the fair value hierarchy.

The fair values of the Company’s marketable securities are based on prices obtained from independent pricing sources. Consistent with the fair value hierarchy described in Note 2, Summary of Significant Accounting Policies, marketable securities with validated quotes from pricing services are reflected within Level 2, as they are primarily based on observable pricing for similar assets or other market observable inputs. Typical inputs used by these pricing services include, but are not limited to, reported trades, benchmark yields, issuer spreads, bids, offers or estimates of cash flow,

prepayment spreads and default rates. The Company performs validation procedures to ensure the reasonableness of this data. The Company performs its own review of prices received from the independent pricing services by comparing these prices to other sources. After completing the validation procedures, the Company did not adjust or override any fair value measurements provided by the pricing services as of September 30, 2023 and December 31, 2022.

The following tables summarize the Company’s cash equivalents and marketable securities as of September 30, 2023 and December 31, 2022:


	September 30, 2023
	Total		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in thousands)
Cash equivalents:
Money market funds	$	139,770	$	139,770	$	—	$	—
U.S. corporate bonds		4,993		—		4,993		—
U.S. commercial paper		2,984		—		2,984		—
Total cash equivalents		147,747		139,770		7,977		—
Marketable securities:
U.S. government securities		202,623		—		202,623		—
U.S. corporate bonds		178,570		—		178,570		—
International corporate bonds		70,911		—		70,911		—
U.S. commercial paper		34,118		—		34,118		—
International commercial paper		72,554		—		72,554		—
U.S. certificates of deposit		10,217		—		10,217		—
U.S. municipal securities		158,347		—		158,347		—
Total marketable securities		727,340		—		727,340		—
	$	875,087	$	139,770	$	735,317	$	—


	December 31, 2022
	Total		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in thousands)
Cash equivalents:
Money market funds	$	161,185	$	161,185	$	—	$	—
Total cash equivalents		161,185		161,185		—		—
Marketable securities:
U.S. government securities		302,911		—		302,911		—
U.S. corporate bonds		354,495		—		354,495		—
International corporate bonds		127,248		—		127,248		—
U.S. commercial paper		63,114		—		63,114		—
International commercial paper		133,163		—		133,163		—
U.S. certificates of deposit		15,613		—		15,613		—
U.S. municipal securities		113,250		—		113,250		—
Total marketable securities		1,109,794		—		1,109,794		—
	$	1,270,979	$	161,185	$	1,109,794	$	—

During the nine months ended September 30, 2023 and 2022, there were no transfers among the Level 1, Level 2 and Level 3 categories.

The following tables summarize the gross unrealized gains and losses of the Company’s marketable securities as of September 30, 2023 and December 31, 2022:


	September 30, 2023
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Credit Losses		Fair Value
	(in thousands)
Assets:
U.S. government securities	$	203,722	$	1	$	(1,100	)	$	—	$	202,623
U.S. corporate bonds		179,873		—		(1,303	)		—		178,570
International corporate bonds		71,351		—		(440	)		—		70,911
U.S. commercial paper		34,144		—		(26	)		—		34,118
International commercial paper		72,646		—		(92	)		—		72,554
U.S. certificates of deposit		10,217		—		—			—		10,217
U.S. municipal securities		159,122		1		(776	)		—		158,347
	$	731,075	$	2	$	(3,737	)	$	—	$	727,340


	December 31, 2022
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Credit Losses		Fair Value
	(in thousands)
Assets:
U.S. government securities	$	307,173	$	—	$	(4,262	)	$	—	$	302,911
U.S. corporate bonds		358,019		6		(3,530	)		—		354,495
International corporate bonds		128,374		7		(1,133	)		—		127,248
U.S. commercial paper		63,234		—		(120	)		—		63,114
International commercial paper		133,338		—		(175	)		—		133,163
U.S. certificates of deposit		15,613		—		—			—		15,613
U.S. municipal securities		114,249		31		(1,030	)		—		113,250
	$	1,120,000	$	44	$	(10,250	)	$	—	$	1,109,794

The following tables summarize the fair value and the unrealized losses of the Company’s marketable securities that have been in a loss position for either less than twelve months or greater than twelve months as of September 30, 2023 and December 31, 2022:


	September 30, 2023
	Less than 12 months					Greater than 12 months					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	(in thousands)
U.S. government securities	$	124,728	$	(394	)	$	63,985	$	(706	)	$	188,713	$	(1,100	)
U.S. corporate bonds		123,313		(703	)		52,280		(600	)		175,593		(1,303	)
International corporate bonds		59,032		(354	)		8,608		(86	)		67,640		(440	)
U.S. commercial paper		26,665		(26	)		—		—			26,665		(26	)
International commercial paper		61,521		(92	)		—		—			61,521		(92	)
U.S. municipal securities		116,609		(519	)		33,740		(257	)		150,349		(776	)
	$	511,868	$	(2,088	)	$	158,613	$	(1,649	)	$	670,481	$	(3,737	)


	December 31, 2022
	Less than 12 months					Greater than 12 months					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	(in thousands)
U.S. government securities	$	112,243	$	(1,517	)	$	185,691	$	(2,745	)	$	297,934	$	(4,262	)
U.S. corporate bonds		208,507		(1,989	)		130,633		(1,541	)		339,140		(3,530	)
International corporate bonds		50,982		(497	)		68,993		(636	)		119,975		(1,133	)
U.S. commercial paper		24,768		(120	)		—		—			24,768		(120	)
International commercial paper		30,987		(175	)		—		—			30,987		(175	)
U.S. municipal securities		86,251		(497	)		14,466		(533	)		100,717		(1,030	)
	$	513,738	$	(4,795	)	$	399,783	$	(5,455	)	$	913,521	$	(10,250	)

As of September 30, 2023 and December 31, 2022, the unrealized losses on the Company’s investments in U.S. government securities, U.S. corporate bonds, and international corporate bonds were caused by interest rate increases. The Company purchased those investments at a premium relative to their face amount. The current credit ratings are all within the guidelines of the investment policy of the Company and the Company does not expect the issuers to settle any security at a price less than the amortized cost basis of the investment. As of September 30, 2023, the Company does not intend to sell those investments and it is not probable that the Company will be required to sell the investments before recovery of their amortized cost basis.

As of September 30, 2023, all marketable securities held by the Company had remaining contractual maturities of one year or less, except for U.S. government securities, U.S. corporate bonds, international corporate bonds and municipal securities with a fair value of $82.3 million and maturities of one to two years.

As of December 31, 2022, all marketable securities held by the Company had remaining contractual maturities of one year or less, except for U.S. government securities, U.S. corporate bonds, international corporate bonds and municipal securities with a fair value of $211.2 million and maturities of one to two years.

All marketable securities, including those with remaining contractual maturities of more than one year, are classified as current assets on the balance sheet because they are considered to be “available for sale” and the Company can convert them into cash to fund current operations.

There have been no impairments of the Company’s assets measured and carried at fair value during the nine months ended September 30, 2023 and the year ended December 31, 2022.

Commitments and Contingencies

9 Months Ended

Sep. 30, 2023

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

License Agreements

CyDex License Agreement

In September 2015, the Company amended and restated its existing commercial license agreement with CyDex Pharmaceuticals, Inc. (“CyDex”), a wholly owned subsidiary of Ligand Pharmaceuticals Incorporated. Under the terms of the commercial license agreement as amended and restated, CyDex has granted to the Company an exclusive license to CyDex’s Captisol drug formulation technology and related intellectual property for the manufacture of pharmaceutical products incorporating brexanolone and the Company’s compound known as SAGE-689, and the development and commercialization of the resulting products for the treatment, prevention or diagnosis of any disease or symptom in humans or animals other than (i) the ocular treatment of any disease or condition with a formulation, including a hormone; (ii) topical ocular treatment of inflammatory conditions; (iii) treatment and prophylaxis of fungal infections in humans; and (iv) any ocular treatment for retinal degeneration. The Company is required to pay a royalty to CyDex on sales of brexanolone and will be required to pay a royalty on any sales of SAGE-689, if such product candidate is successfully developed in the future. Royalty rates are in the low single digits based on levels of net sales. From the effective date of the agreement to September 30, 2023, the Company has paid to CyDex $1.0 million for licensing fees, which was recorded as research and development expense.

Under the amended and restated license agreement with CyDex, the Company agreed to make milestone payments on the achievement of clinical development and regulatory milestones in the amount of up to $0.8 million in clinical milestones and up to $3.8 million in regulatory milestones for each of the first two fields with respect to brexanolone; up to $1.3 million in clinical milestones and up to $8.5 million in regulatory milestones for each of the third and fourth fields with respect to brexanolone; and up to $0.8 million in clinical milestones and up to $1.8 million in regulatory milestones for one field with respect to SAGE-689. From the effective date of the agreement to September 30, 2023, the Company has recorded research and development expense and made cash payments of $3.6 million related to these clinical development and regulatory milestones and has recorded an intangible asset and made a cash payment of $3.0 million related to these regulatory milestones.

For the nine months ended September 30, 2023 and 2022, the Company did not record any expense or intangible asset, or make any milestone payments related to clinical development or regulatory milestones for the brexanolone program or SAGE-689 under the license agreement with CyDex.

University of California License Agreements

In October 2013, the Company entered into a non-exclusive license agreement with the Regents of the University of California (“the Regents”) under which the Company was granted a non-exclusive license to certain clinical data and clinical material related to brexanolone for use in the development and commercialization of biopharmaceutical products in the licensed field, including status epilepticus and postpartum depression. In May 2014, the license agreement was amended to add the treatment of essential tremor to the licensed field of use, materials and milestone fee provisions of the agreement. The Company paid to the Regents clinical development milestones of $0.1 million, prior to December 31, 2015; no other milestones are outstanding under this non-exclusive license agreement. The Company is required to pay royalties of less than 1% on net sales for a period of fifteen years following the sale of the first product developed using the data and materials, and the Company began to pay these royalties in 2019. The license will terminate on the earlier to occur of (i) 27 years after the effective date or (ii) 15 years after the last-derived product is first commercially sold.

In June 2015, the Company entered into an exclusive license agreement with the Regents whereby the Company was granted an exclusive license to certain patent rights related to the use of allopregnanolone to treat various diseases. In exchange for such license, the Company paid an upfront payment of $50,000 and was required to make payments of $15,000 for annual maintenance fees until the calendar year following the first sale of ZULRESSO. The Company is obligated to make milestone payments following the achievement of specified regulatory and sales milestones of up to $0.7 million and $2.0 million in the aggregate, respectively. The Company pays royalties at a low single digit percentage of net sales of ZULRESSO, subject to specified minimum annual royalty amounts. Unless terminated by operation of law or by acts of the parties under the terms of the agreement, the license agreement will terminate when the last-to-expire patents or last-to-be abandoned patent applications expire, whichever is later. From the effective date of the agreement to September 30, 2023, the Company has recorded research and development expense and made cash payments of $0.3 million related to these regulatory and sales milestones; and has recorded an intangible asset and made a cash payment of $0.5 million related to these regulatory and sales milestones.

For the nine months ended September 30, 2023 and 2022, the Company did not record any expense or make any milestone payments under the license agreements with the Regents.

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	59,970,549	59,512,158
Common stock, shares outstanding	59,967,516	59,509,125
Treasury stock, shares	3,033	3,033

Fair Value Measurements - Summary of Fair Value And Unrealized Losses of Marketable Securities In Loss Position (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	$ 511,868	$ 513,738
Less than 12 months, Unrealized Losses	(2,088)	(4,795)
Greater than 12 months, Fair Value	158,613	399,783
Greater than 12 months, Unrealized Losses	(1,649)	(5,455)
Fair Value	670,481	913,521
Unrealized Losses	(3,737)	(10,250)
U.S. Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	124,728	112,243
Less than 12 months, Unrealized Losses	(394)	(1,517)
Greater than 12 months, Fair Value	63,985	185,691
Greater than 12 months, Unrealized Losses	(706)	(2,745)
Fair Value	188,713	297,934
Unrealized Losses	(1,100)	(4,262)
U.S. Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	123,313	208,507
Less than 12 months, Unrealized Losses	(703)	(1,989)
Greater than 12 months, Fair Value	52,280	130,633
Greater than 12 months, Unrealized Losses	(600)	(1,541)
Fair Value	175,593	339,140
Unrealized Losses	(1,303)	(3,530)
International Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	59,032	50,982
Less than 12 months, Unrealized Losses	(354)	(497)
Greater than 12 months, Fair Value	8,608	68,993
Greater than 12 months, Unrealized Losses	(86)	(636)
Fair Value	67,640	119,975
Unrealized Losses	(440)	(1,133)
U.S. Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	26,665	24,768
Less than 12 months, Unrealized Losses	(26)	(120)
Fair Value	26,665	24,768
Unrealized Losses	(26)	(120)
International Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	61,521	30,987
Less than 12 months, Unrealized Losses	(92)	(175)
Fair Value	61,521	30,987
Unrealized Losses	(92)	(175)
U.S. Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	116,609	86,251
Less than 12 months, Unrealized Losses	(519)	(497)
Greater than 12 months, Fair Value	33,740	14,466
Greater than 12 months, Unrealized Losses	(257)	(533)
Fair Value	150,349	100,717
Unrealized Losses	$ (776)	$ (1,030)

Commitments and Contingencies - CyDex License Agreement - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Commitments And Contingencies [Line Items]
Research and development expense	$ 101,919,000	$ 81,553,000	$ 291,905,000	$ 236,868,000
CyDex License Agreement [Member]
Commitments And Contingencies [Line Items]
Research and development expense			1,000,000.0
CyDex License Agreement [Member] \| Brexanolone [Member]
Commitments And Contingencies [Line Items]
Research and development expense related to milestone expense			0
Milestone payments			0
CyDex License Agreement [Member] \| First and Second Clinical Development Milestones [Member] \| Brexanolone [Member] \| Maximum [Member]
Commitments And Contingencies [Line Items]
Expected milestone payments	800,000		800,000
CyDex License Agreement [Member] \| First and Second Regulatory Milestones [Member] \| Brexanolone [Member] \| Maximum [Member]
Commitments And Contingencies [Line Items]
Expected milestone payments	3,800,000		3,800,000
CyDex License Agreement [Member] \| Third and Fourth Clinical Development Milestones [Member] \| Brexanolone [Member] \| Maximum [Member]
Commitments And Contingencies [Line Items]
Expected milestone payments	1,300,000		1,300,000
CyDex License Agreement [Member] \| Third and Fourth Regulatory Milestones [Member] \| Brexanolone [Member] \| Maximum [Member]
Commitments And Contingencies [Line Items]
Expected milestone payments	8,500,000		8,500,000
CyDex License Agreement [Member] \| Clinical Development [Member] \| Brexanolone [Member]
Commitments And Contingencies [Line Items]
Milestone payments related to intangible assets			0
CyDex License Agreement [Member] \| Clinical Development [Member] \| SAGE-689 [Member] \| Maximum [Member]
Commitments And Contingencies [Line Items]
Expected milestone payments	800,000		800,000
CyDex License Agreement [Member] \| Regulatory Milestones [Member] \| Brexanolone [Member]
Commitments And Contingencies [Line Items]
Research and development expense related to milestone expense			0
Milestone payments			0
Intangible asset related to milestone	0		0
Milestone payments related to intangible assets			0
CyDex License Agreement [Member] \| Regulatory Milestones [Member] \| SAGE-689 [Member] \| Maximum [Member]
Commitments And Contingencies [Line Items]
Expected milestone payments	1,800,000		1,800,000
CyDex License Agreement [Member] \| Clinical Development and Regulatory Milestones [Member]
Commitments And Contingencies [Line Items]
Research and development expense related to milestone expense			3,600,000
Milestone payments			3,600,000
Intangible asset related to milestone	$ 3,000,000.0		$ 3,000,000.0

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Pay vs Performance Disclosure
Net Income (Loss)	$ (201,630)	$ (160,325)	$ (146,828)	$ (137,323)	$ (126,260)	$ (122,055)	$ (508,783)	$ (385,638)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-Publisher FASB
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 45
-Paragraph 1A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482790/220-10-45-1A

Reference 37: http://www.xbrl.org/2003/role/disclosureRef
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Reference 38: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 39: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
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-Subparagraph (SX 210.9-04(22))
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-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

+ Details

Net Loss Per Share

9 Months Ended

Sep. 30, 2023

Earnings Per Share [Abstract]

Net Loss Per Share

The following table shows the calculation of basic and diluted net loss per share for the three and nine months ended September 30, 2023 and 2022:


	Three Months Ended September 30,						Nine Months Ended September 30,
	2023			2022			2023			2022
Basic net loss per share:
Numerator:
Net loss (in thousands)	$	(201,630	)	$	(137,323	)	$	(508,783	)	$	(385,638	)
Denominator:
Weighted average common stock outstanding - basic and diluted		59,912,378			59,428,123			59,786,254			59,242,563
Net loss per share - basic and diluted	$	(3.37	)	$	(2.31	)	$	(8.51	)	$	(6.51	)

The following table summarizes common stock equivalents outstanding that were excluded from the calculation of diluted net loss per share because including them would have been anti-dilutive as of September 30, 2023 and 2022:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Stock options		7,676,962		7,017,873		7,676,962		7,017,873
Restricted stock units		1,721,304		179,676		1,721,304		179,676
Employee stock purchase plan		25,649		43,877		25,649		43,877
		9,423,915		7,241,426		9,423,915		7,241,426

Stock options and restricted stock units that are outstanding and contain performance-based vesting criteria for which the performance conditions have not been met are excluded from the calculation of common stock equivalents outstanding.

Accrued Expenses - Summary of Accrued Expenses (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued research and development costs	$ 63,386	$ 32,565
Restructuring	24,250
Employee-related	14,108	29,372
Professional services	12,497	10,172
Other	660	557
Total accrued expenses	$ 114,901	$ 72,666

Commitments and Contingencies - University of California License Agreements - Additional Information (Detail) - University of California License Agreements [Member] - USD ($)		1 Months Ended	9 Months Ended		12 Months Ended	100 Months Ended
	Dec. 31, 2015	Jun. 30, 2015	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2015	Sep. 30, 2023
Commitments And Contingencies [Line Items]
Upfront payment		$ 50,000
Annual license maintenance fee					$ 15,000
Milestone payments			$ 0	$ 0
After The Effective Date [Member]
Commitments And Contingencies [Line Items]
Licenses Expiration period, maximum	27 years
After The First Sale [Member]
Commitments And Contingencies [Line Items]
Licenses Expiration period, maximum	15 years
Clinical Development [Member]
Commitments And Contingencies [Line Items]
Milestone payments	$ 100,000
Milestone outstanding	$ 0
Clinical Development [Member] \| Maximum [Member]
Commitments And Contingencies [Line Items]
Percentage of net sales paid as royalties	1.00%
Regulatory Milestones [Member] \| Maximum [Member]
Commitments And Contingencies [Line Items]
Expected milestone payments		700,000
Sales Milestones [Member] \| Maximum [Member]
Commitments And Contingencies [Line Items]
Expected milestone payments		$ 2,000,000.0
Regulatory and Sales Milestones [Member]
Commitments And Contingencies [Line Items]
Research and development expense related to milestone expense						$ 300,000
Milestone payments						300,000
Intangible asset related to milestone			$ 500,000			500,000
Milestone payments related to intangible assets						$ 500,000

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2023	Oct. 31, 2023
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Trading Symbol	SAGE
Entity Registrant Name	Sage Therapeutics, Inc.
Entity Central Index Key	0001597553
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding		59,967,516
Entity Shell Company	false
Entity File Number	001-36544
Entity Tax Identification Number	27-4486580
Entity Address, Address Line One	215 First Street
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02142
City Area Code	617
Local Phone Number	299-8380
Entity Interactive Data Current	Yes
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false

Net Loss Per Share (Tables)

9 Months Ended

Sep. 30, 2023

Earnings Per Share [Abstract]

Summary of Basic and Diluted Net Loss Per Share

The following table shows the calculation of basic and diluted net loss per share for the three and nine months ended September 30, 2023 and 2022:


	Three Months Ended September 30,						Nine Months Ended September 30,
	2023			2022			2023			2022
Basic net loss per share:
Numerator:
Net loss (in thousands)	$	(201,630	)	$	(137,323	)	$	(508,783	)	$	(385,638	)
Denominator:
Weighted average common stock outstanding - basic and diluted		59,912,378			59,428,123			59,786,254			59,242,563
Net loss per share - basic and diluted	$	(3.37	)	$	(2.31	)	$	(8.51	)	$	(6.51	)

Summary of Anti-Dilutive Common Stock Equivalents Outstanding


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Stock options		7,676,962		7,017,873		7,676,962		7,017,873
Restricted stock units		1,721,304		179,676		1,721,304		179,676
Employee stock purchase plan		25,649		43,877		25,649		43,877
		9,423,915		7,241,426		9,423,915		7,241,426

Stock-Based Compensation - Summary of Activity Relating to Restricted Stock Units (Detail)	9 Months Ended
	Sep. 30, 2023 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding, Shares at beginning balance \| shares	1,415,481
Granted, Shares \| shares	2,594,486
Vested, Shares \| shares	(236,852)
Forfeited, Shares \| shares	(484,311)
Outstanding, Shares at ending balance \| shares	3,288,804
Outstanding, Weighted Average Grant Date Fair Value at beginning balance \| $ / shares	$ 48.73
Granted, Weighted Average Grant Date Fair Value \| $ / shares	30.55
Vested, Weighted Average Grant Date Fair Value \| $ / shares	56.32
Forfeited, Weighted Average Grant Date Fair Value \| $ / shares	43.37
Outstanding, Weighted Average Grant Date Fair Value at ending balance \| $ / shares	$ 34.63

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 1D
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-1D

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
-Section 35
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
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-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (a)(2)
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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Reference 24: http://www.xbrl.org/2003/role/disclosureRef
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Reference 25: http://www.xbrl.org/2003/role/disclosureRef
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Reference 26: http://www.xbrl.org/2003/role/disclosureRef
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Reference 27: http://www.xbrl.org/2003/role/disclosureRef
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Reference 28: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (f)(2)(v)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

+ Details

Restructuring

9 Months Ended

Sep. 30, 2023

Restructuring and Related Activities [Abstract]

Restructuring

9. Restructuring

In August 2023, the Company implemented a strategic corporate reorganization and reprioritization of its pipeline. The reorganization included a reduction of the Company’s workforce by approximately 40%, designed to right-size the organization as the Company works to achieve sustained growth and support the goal of a successful launch of ZURZUVAE to treat women with PPD. During the three months ended September 30, 2023, the Company recorded $33.6 million of expense for restructuring, primarily for one-time termination benefits to the affected employees, primarily for cash payments of severance, healthcare benefits and outplacement assistance.

The Company expects that substantially all of the accrued restructuring charges as of September 30, 2023 will be paid in cash by March 31, 2024. Total restructuring charges expected to be incurred are $36.9 million, including $3.3 million of expense which will be recorded in future periods, primarily for one-time termination benefits.

The following table summarizes activity related to the restructuring accrual:


	Restructuring accrual
	(in thousands)
Balance as of July 1, 2023	$	-
Restructuring expenses incurred		33,599
Cash paid		(5,715	)
Non-cash activity		(3,634	)
Balance as of September 30, 2023	$	24,250

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2023

Fair Value Disclosures [Abstract]

Summary of Company's Cash Equivalents and Marketable Securities

The following tables summarize the Company’s cash equivalents and marketable securities as of September 30, 2023 and December 31, 2022:


	September 30, 2023
	Total		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in thousands)
Cash equivalents:
Money market funds	$	139,770	$	139,770	$	—	$	—
U.S. corporate bonds		4,993		—		4,993		—
U.S. commercial paper		2,984		—		2,984		—
Total cash equivalents		147,747		139,770		7,977		—
Marketable securities:
U.S. government securities		202,623		—		202,623		—
U.S. corporate bonds		178,570		—		178,570		—
International corporate bonds		70,911		—		70,911		—
U.S. commercial paper		34,118		—		34,118		—
International commercial paper		72,554		—		72,554		—
U.S. certificates of deposit		10,217		—		10,217		—
U.S. municipal securities		158,347		—		158,347		—
Total marketable securities		727,340		—		727,340		—
	$	875,087	$	139,770	$	735,317	$	—


	December 31, 2022
	Total		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in thousands)
Cash equivalents:
Money market funds	$	161,185	$	161,185	$	—	$	—
Total cash equivalents		161,185		161,185		—		—
Marketable securities:
U.S. government securities		302,911		—		302,911		—
U.S. corporate bonds		354,495		—		354,495		—
International corporate bonds		127,248		—		127,248		—
U.S. commercial paper		63,114		—		63,114		—
International commercial paper		133,163		—		133,163		—
U.S. certificates of deposit		15,613		—		15,613		—
U.S. municipal securities		113,250		—		113,250		—
Total marketable securities		1,109,794		—		1,109,794		—
	$	1,270,979	$	161,185	$	1,109,794	$	—

Summary of Gross Unrealized Gains and Losses of Marketable Securities

The following tables summarize the gross unrealized gains and losses of the Company’s marketable securities as of September 30, 2023 and December 31, 2022:


	September 30, 2023
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Credit Losses		Fair Value
	(in thousands)
Assets:
U.S. government securities	$	203,722	$	1	$	(1,100	)	$	—	$	202,623
U.S. corporate bonds		179,873		—		(1,303	)		—		178,570
International corporate bonds		71,351		—		(440	)		—		70,911
U.S. commercial paper		34,144		—		(26	)		—		34,118
International commercial paper		72,646		—		(92	)		—		72,554
U.S. certificates of deposit		10,217		—		—			—		10,217
U.S. municipal securities		159,122		1		(776	)		—		158,347
	$	731,075	$	2	$	(3,737	)	$	—	$	727,340


	December 31, 2022
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Credit Losses		Fair Value
	(in thousands)
Assets:
U.S. government securities	$	307,173	$	—	$	(4,262	)	$	—	$	302,911
U.S. corporate bonds		358,019		6		(3,530	)		—		354,495
International corporate bonds		128,374		7		(1,133	)		—		127,248
U.S. commercial paper		63,234		—		(120	)		—		63,114
International commercial paper		133,338		—		(175	)		—		133,163
U.S. certificates of deposit		15,613		—		—			—		15,613
U.S. municipal securities		114,249		31		(1,030	)		—		113,250
	$	1,120,000	$	44	$	(10,250	)	$	—	$	1,109,794

Summary of Fair Value And Unrealized Losses of Marketable Securities In Loss Position


	September 30, 2023
	Less than 12 months					Greater than 12 months					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	(in thousands)
U.S. government securities	$	124,728	$	(394	)	$	63,985	$	(706	)	$	188,713	$	(1,100	)
U.S. corporate bonds		123,313		(703	)		52,280		(600	)		175,593		(1,303	)
International corporate bonds		59,032		(354	)		8,608		(86	)		67,640		(440	)
U.S. commercial paper		26,665		(26	)		—		—			26,665		(26	)
International commercial paper		61,521		(92	)		—		—			61,521		(92	)
U.S. municipal securities		116,609		(519	)		33,740		(257	)		150,349		(776	)
	$	511,868	$	(2,088	)	$	158,613	$	(1,649	)	$	670,481	$	(3,737	)


	December 31, 2022
	Less than 12 months					Greater than 12 months					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	(in thousands)
U.S. government securities	$	112,243	$	(1,517	)	$	185,691	$	(2,745	)	$	297,934	$	(4,262	)
U.S. corporate bonds		208,507		(1,989	)		130,633		(1,541	)		339,140		(3,530	)
International corporate bonds		50,982		(497	)		68,993		(636	)		119,975		(1,133	)
U.S. commercial paper		24,768		(120	)		—		—			24,768		(120	)
International commercial paper		30,987		(175	)		—		—			30,987		(175	)
U.S. municipal securities		86,251		(497	)		14,466		(533	)		100,717		(1,030	)
	$	513,738	$	(4,795	)	$	399,783	$	(5,455	)	$	913,521	$	(10,250	)

- Definition

Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-9

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
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+ Details

Accrued Expenses - Additional Information (Details) $ in Millions	Sep. 30, 2023 USD ($)
Payables and Accruals [Line Items]
Purchase commitment, cancelling excess amount committed	$ 28.9

Nature of the Business - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended	162 Months Ended
	Sep. 30, 2023	Dec. 31, 2020	Sep. 30, 2023	Dec. 31, 2022
Nature Of Business [Line Items]
Accumulated deficit	$ 2,536,953		$ 2,536,953	$ 2,028,170
Net income from up-front		$ 606,100
Up-front payments receive	1,000,000
Redeemable Convertible Preferred Stock [Member] \| Convertible Notes [Member] \| Initial Public Offering [Member]
Nature Of Business [Line Items]
Accumulated deficit	$ 2,500,000		2,500,000
Net proceeds from sale of equity and notes			$ 2,800,000

- Definition

Amount of accumulated undistributed earnings (deficit).

+ References + Details

Summary of Significant Accounting Policies - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2023
Product Revenue [Member]
Summary Of Significant Accounting Policies [Line Items]
Incremental costs incurred expected amortization period of asset	true

Stock-Based Compensation

9 Months Ended

Sep. 30, 2023

Share-Based Payment Arrangement [Abstract]

Stock-Based Compensation

Equity Plans

On July 2, 2014, the stockholders of the Company approved the 2014 Stock Option and Incentive Plan (the “2014 Plan”), which became effective immediately prior to the completion of the Company’s IPO. The 2014 Plan provides for the grant of restricted stock awards, restricted stock units, incentive stock options and non-statutory stock options. The 2014 Plan replaced the Company’s 2011 Stock Option and Grant Plan (the “2011 Plan”). The Company no longer grants stock options or other awards under its 2011 Plan, but any stock options outstanding under the 2011 Plan remain outstanding and effective in accordance with their terms.

The 2014 Plan provides for an annual increase, to be added on the first day of each year, by up to 4% of the Company’s outstanding shares of common stock as of the last day of the prior year. On January 1, 2023, 2,380,365 shares of common stock, representing 4% of the Company’s outstanding shares of common stock as of December 31, 2022, were added to the 2014 Plan.

On December 15, 2016, the Board of Directors of the Company (the “Board”) approved the 2016 Inducement Equity Plan (as amended and restated, the “2016 Plan”). The 2016 Plan provides for the grant of equity awards to individuals who have not previously been an employee or a non-employee director of the Company to induce them to accept

employment and to provide them with a proprietary interest in the Company. On September 20, 2018, the Board amended the 2016 Plan to increase the total number of shares reserved for issuance by 1,200,000 shares.

Terms of equity grants, including vesting requirements, are determined by the Board or the Compensation Committee of the Board, subject to the provisions of the applicable plan. Stock options granted by the Company that are not performance-based are considered time-based because they vest based on the continued service of the grantee with the Company during a specified period following grant. These awards, when granted to employees, generally vest ratably over four years, with 25% vesting at the one-year anniversary. All stock option awards expire 10 years after the date of grant.

As of September 30, 2023, the total number of shares underlying outstanding awards under all equity plans was 11,420,766 and the total number of shares available for future issuance under all equity plans was 7,283,210 shares.

On June 16, 2022, the Company’s stockholders approved an amendment to the amended 2014 Employee Stock Purchase Plan (the “ESPP”), which had been previously approved by the Board, to add 300,000 shares of common stock to the ESPP. On June 15, 2023, the Company’s stockholders approved another amendment to the ESPP, which had been previously approved by the Board, to add an additional 500,000 shares of common stock to the ESPP. As amended, a total of 1,082,000 shares of common stock have been authorized for issuance under the ESPP.

Restricted Stock Units

The following table summarizes activity relating to time-based restricted stock units and performance restricted stock units:


	Shares			Weighted Average Grant Date Fair Value
Outstanding as of December 31, 2022		1,415,481		$	48.73
Granted		2,594,486		$	30.55
Vested		(236,852	)	$	56.32
Forfeited		(484,311	)	$	43.37
Outstanding as of September 30, 2023		3,288,804		$	34.63

Time-based restricted stock units

During the year ended December 31, 2020, the Company granted 550,890 time-based restricted stock units to certain employees of the Company. These time-based restricted stock units vested over two years, with 25% vesting at the one-year anniversary of the grant date and 75% vesting at the two-year anniversary of the grant date, which were in April 2021 and April 2022, respectively. During the year ended December 31, 2021, 113,941 of these time-based restricted stock units vested, with a fair value on the date of vesting equal to $8.8 million. During the three months ended June 30, 2022, 291,505 of these time-based restricted stock units vested, with a fair value on the date of vesting equal to $9.5 million. During the three months ended March 31, 2022, no time-based restricted stock units vested.

During the year ended December 31, 2021, the Company granted 268,119 time-based restricted stock units to certain employees of the Company that vest over four years. In September 2022, 25% vested on the one-year anniversary of the vesting start date and the remaining 75% vest ratably in quarterly increments over the remaining three years. During the three and nine months ended September 30, 2023, 12,385 and 40,962, respectively, of these time-based restricted stock units vested, with a fair value of $0.2 million and $1.6 million, respectively, on the dates of vesting. During the three months ended September 30, 2022, 59,950 of these time-based restricted stock units vested, with a fair value of $2.3 million on the date of vesting.

During the nine months ended September 30, 2022, the Company granted no time-based restricted stock units.

During the three months ended March 31, 2023, the Company granted 330,617 time-based restricted stock units to certain employees and consultants of the Company. These time-based restricted stock units vest over four years, with 25% vesting at the one-year anniversary of the vesting start date and the remaining 75% vesting in equal installments on each anniversary of the vesting start date for the following three years.

During the three months ended June 30, 2023, the Company granted no time-based restricted stock units.

During the three months ended September 30, 2023, the Company granted 1,382,300 time-based restricted stock units to certain employees of the Company. These time-based restricted stock units vest in February 2025.

As of September 30, 2023, 1,721,304 time-based restricted stock units were both outstanding and unvested, and the total unrecognized stock-based compensation expense related to these awards was $42.0 million.

Performance restricted stock units

During the three months ended September 30, 2023 and 2022, the Company granted 19,248 and 57,480 performance restricted stock units, respectively, to its employees and consultants. The majority of the performance restricted stock units granted during the three months ended September 30, 2023 and 2022 vest upon the achievement of certain clinical and regulatory development milestones related to product candidates and certain commercial milestones.

During the nine months ended September 30, 2023 and 2022, the Company granted 881,569 and 569,410 performance restricted stock units, respectively, to its employees and consultants. The majority of the performance restricted stock units granted during the nine months ended September 30, 2023 and 2022 vest upon the achievement of certain clinical and regulatory development milestones related to product candidates and certain commercial milestones. Certain performance restricted stock units granted during the three months ended March 31, 2023 vest upon the Company reaching specified measures of total stockholder return.

Recognition of stock-based compensation expense associated with performance restricted stock units, except for those with milestones that are measures of total stockholder return, commences when the performance condition is considered probable of achievement, using management’s best estimates, which consider the inherent risk and uncertainty regarding the future outcomes of the milestones. Recognition of stock-based compensation associated with performance restricted stock units with milestones that are measures of total stockholder return commences on the grant date and is recorded independently of the vesting outcomes of the grants.

As of September 30, 2022, for performance restricted stock units that were outstanding, the achievement of the milestones that had not been met was considered not probable, and therefore no expense has been recognized related to these awards during the nine months ended September 30, 2022. During the nine months ended September 30, 2022, no performance restricted stock units vested.

During the three months ended March 31, 2023, one regulatory development milestone for outstanding performance restricted stock units was achieved. The fair value of the performance restricted stock units that vested upon achievement was $5.5 million and the Company recognized stock-based compensation expense related to this milestone of $8.5 million. 27% of the performance restricted stock units that were granted during the year ended December 31, 2021 included this milestone as a vesting condition.

During the three months ended June 30, 2023, no performance restricted stock units vested.

During the three months ended September 30, 2023, one regulatory development milestone for outstanding performance restricted stock units was achieved. The fair value of the performance restricted stock units that vested upon achievement was $2.6 million and the Company recognized stock-based compensation expense related to this milestone of $2.9 million. Performance restricted stock units that included this milestone as a vesting condition were granted during the nine months ended September 30, 2023, and the years ended December 31, 2022 and 2021.

During the three months ended September 30, 2023, the achievement of one commercial milestone that is the criteria for vesting of performance restricted stock units was considered probable, but had not been met, and therefore $2.7 million of stock-based compensation expense was recognized related to these awards for the three months ended September 30, 2023. Performance restricted stock units with this milestone were granted during the year ended December 31, 2020. As of June 30, 2023, for performance restricted stock units that were outstanding, the achievement of the milestones that had not been met was considered not probable, and therefore no expense has been recognized related to these awards during the six months ended June 30, 2023.

As of September 30, 2023, 1,567,500 performance restricted stock units were both outstanding and unvested, and the total unrecognized stock-based compensation expense related to these awards was $71.6 million. Of this amount, during the three months ended September 30, 2023, the achievement of one commercial milestone that is the criteria for vesting of performance restricted stock units was considered probable, but had not been met, and therefore $2.7 million of stock-based compensation expense was recognized related to these awards for the three months ended September 30, 2023.

Stock Option Rollforward

The following table summarizes activity related to time-based and performance-based stock options:


	Shares			Weighted Average Exercise Price		Weighted Average Remaining Life (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding as of December 31, 2022		7,788,350		$	77.95		6.36	$	7,275
Granted		919,751		$	45.76
Exercised		(65,940	)	$	16.58
Forfeited		(510,199	)	$	56.31
Outstanding as of September 30, 2023		8,131,962		$	76.17		5.91	$	371
Exercisable as of September 30, 2023		5,934,180		$	82.73		5.00	$	370

As of September 30, 2023, the Company had unrecognized stock-based compensation expense related to its outstanding and unvested time-based stock option awards of $48.9 million, which is expected to be recognized over the remaining weighted average vesting period of 2.75 years.

The intrinsic value of stock options exercised during the nine months ended September 30, 2023 and 2022 was $1.9 million and $4.4 million, respectively.

Performance-Based Stock Options

Recognition of stock-based compensation expense associated with performance-based stock options commences when the performance condition is considered probable of achievement, using management’s best estimates, which consider the inherent risk and uncertainty regarding the future outcomes of the milestones.

As of September 30, 2023 and 2022, for performance-based stock option grants that were outstanding, the achievement of the milestones that had not been met was considered not probable, and therefore no expense has been recognized related to these awards during the nine months ended September 30, 2023 and 2022, respectively.

During the nine months ended September 30, 2023 and 2022, the Company granted no stock options to purchase shares of common stock that contain performance-based vesting criteria.

During the three months ended September 30, 2023, one regulatory development milestone was achieved under performance-based stock options granted in connection with the hiring of its chief executive officer. Stock options with this milestone were granted during the year ended December 31, 2021. This milestone represented 30% of the performance-based stock option grants that were made during the year ended December 31, 2021. During the three months ended September 30, 2023, the Company recognized stock-based compensation expense related to this milestone of $10.7 million.

During the six months ended June 30, 2023, no milestones were achieved under performance-based stock options.

During the nine months ended September 30, 2022, no milestones were achieved under performance-based stock options.

As of September 30, 2023, 455,000 performance-based stock options were both outstanding and unvested, the total unrecognized stock-based compensation expense related to these awards was $24.9 million before the application of the forfeiture rate and the timing of recognition of this stock-based compensation expense is subject to judgment of the Company as to when the performance conditions are considered probable of being achieved.

Stock-Based Compensation Expense

The following table summarizes stock-based compensation expense recognized during the three and nine months ended September 30, 2023 and 2022:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
	(in thousands)
Research and development	$	6,874	$	5,964	$	20,143	$	21,037
Selling, general and administrative		20,979		7,205		39,441		25,321
Restructuring		838		—		838		—
	$	28,691	$	13,169	$	60,422	$	46,358

The following table summarizes stock-based compensation expense by award type recognized during the three and nine months ended September 30, 2023 and 2022:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
	(in thousands)
Stock options	$	20,251	$	11,992	$	39,929	$	40,659
Restricted stock units		8,101		730		19,272		4,982
Employee stock purchase plan		339		447		1,221		717
	$	28,691	$	13,169	$	60,422	$	46,358

For stock option awards, the fair value is estimated at the grant date using the Black-Scholes option-pricing model, taking into account the terms and conditions upon which stock options are granted. The fair value of the stock options is amortized on a straight-line basis for stock option awards to employees, non-employee directors and non-employee consultants over the requisite service period of the awards.

The weighted average grant date fair value per share of stock options granted under the Company’s stock option plans during the nine months ended September 30, 2023 and 2022 was $30.27 and $25.96, respectively.

Insider Trading Arrangements	9 Months Ended
Insider Trading Arrangements	Sep. 30, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Net Loss Per Share - Summary of Anti-Dilutive Common Stock Equivalents Outstanding (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common stock equivalents	9,423,915	7,241,426	9,423,915	7,241,426
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common stock equivalents	7,676,962	7,017,873	7,676,962	7,017,873
Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common stock equivalents	1,721,304	179,676	1,721,304	179,676
Employee Stock Purchase Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common stock equivalents	25,649	43,877	25,649	43,877

Stock-Based Compensation - Summary of Stock-Based Compensation Expense Recognized (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total Stock-based compensation expense	$ 28,691	$ 13,169	$ 60,422	$ 46,358
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total Stock-based compensation expense	6,874	5,964	20,143	21,037
Selling, General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total Stock-based compensation expense	20,979	7,205	39,441	25,321
Restructuring [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total Stock-based compensation expense	$ 838	$ 0	$ 838	$ 0

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 148,712	$ 162,700
Marketable securities	727,340	1,109,794
Prepaid expenses and other current assets	34,705	50,826
Collaboration receivable - related party	$ 22,513	$ 13,660
Accounts Receivable, after Allowance for Credit Loss, Current, Related Party, Type [Extensible Enumeration]	Related Party [Member]	Related Party [Member]
Total current assets	$ 933,270	$ 1,336,980
Property and equipment, net	2,442	2,898
Restricted cash	1,332	1,269
Right-of-use operating asset	6,026	10,532
Other long-term assets	6,593	4,770
Total assets	949,663	1,356,449
Current liabilities:
Accounts payable	11,136	18,950
Accrued expenses	114,901	72,666
Operating lease liability, current portion	6,967	7,643
Total current liabilities	133,004	99,259
Operating lease liability, net of current portion		4,491
Other liabilities		100
Total liabilities	133,004	103,850
Commitments and contingencies (Note 5)
Stockholders’ equity:
Preferred stock, $0.0001 par value per share; 5,000,000 shares authorized at September 30, 2023 and December 31, 2022; no shares issued or outstanding at September 30, 2023 and December 31, 2022
Common stock, $0.0001 par value per share; 120,000,000 shares authorized at September 30, 2023 and December 31, 2022; [OPEN] and 59,512,158 shares issued at September 30, 2023 and December 31, 2022; [OPEN] and 59,509,125 shares outstanding at September 30, 2023 and December 31, 2022	6	6
Treasury stock, at cost, 3,033 shares at September 30, 2023 and December 31, 2022	(400)	(400)
Additional paid-in capital	3,357,741	3,291,369
Accumulated deficit	(2,536,953)	(2,028,170)
Accumulated other comprehensive loss	(3,735)	(10,206)
Total stockholders’ equity	816,659	1,252,599
Total liabilities and stockholders’ equity	$ 949,663	$ 1,356,449

Net Loss Per Share - Summary of Basic and Diluted Net Loss Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Numerator:
Net loss	$ (201,630)	$ (160,325)	$ (146,828)	$ (137,323)	$ (126,260)	$ (122,055)	$ (508,783)	$ (385,638)
Denominator:
Weighted average common stock outstanding - basic	59,912,378			59,428,123			59,786,254	59,242,563
Weighted average common stock outstanding - diluted	59,912,378			59,428,123			59,786,254	59,242,563
Net loss per share - basic	$ (3.37)			$ (2.31)			$ (8.51)	$ (6.51)
Net loss per share - diluted	$ (3.37)			$ (2.31)			$ (8.51)	$ (6.51)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

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-URI https://asc.fasb.org//1943274/2147482635/260-10-55-52

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
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-Name Accounting Standards Codification
-Section 45
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482689/260-10-45-7

+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
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-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-3

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
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-Paragraph 1
-Subparagraph (e)(4)
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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-Topic 260
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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-Publisher FASB
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-Topic 942
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
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+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

Collaboration Agreements (Tables)

9 Months Ended

Sep. 30, 2023

Collaboration Agreement [Abstract]

Summary of Operating Expenses Category Related to Collaboration Agreement

The following table summarizes expenses related to the Biogen Collaboration Agreement that were incurred by the Company and the related reimbursement from Biogen or to Biogen, reflected by category of operating expenses:


	Three Months Ended September 30,						Nine Months Ended September 30,
	2023			2022			2023			2022
	(in thousands)
Expenses related to the Biogen Collaboration Agreement incurred by Sage	$	83,276		$	53,139		$	210,936		$	161,111
Net reimbursement to (from) Biogen reflected in the condensed consolidated statements of operations and comprehensive loss:
Research and development expenses		(28,204	)		(17,867	)		(67,903	)		(57,364	)
Selling, general and administrative expenses		5,835			(480	)		16,345			(4,788	)
		(22,369	)		(18,347	)		(51,558	)		(62,152	)
Total net expenses related to the Biogen Collaboration Agreement in the condensed consolidated statements of operations and comprehensive loss	$	60,907		$	34,792		$	159,378		$	98,959

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash flows from operating activities
Net loss	$ (508,783)	$ (385,638)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	60,422	46,358
Premium on marketable securities	(71)	(1,464)
Amortization of premium (discount) on marketable securities	(12,521)	7,182
Depreciation expense	984	832
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	16,121	(13,176)
Collaboration receivable - related party	(8,853)	58
Other long-term assets	(1,823)	(658)
Right-of-use operating asset	4,506	4,139
Operating lease liabilities, current	(676)	135
Operating lease liabilities, non-current	(4,491)	(4,800)
Accounts payable	(7,677)	(3,357)
Accrued expenses and other liabilities	41,796	17,285
Net cash used in operating activities	(421,066)	(333,104)
Cash flows from investing activities
Proceeds from sales and maturities of marketable securities	861,231	918,816
Purchases of marketable securities	(459,714)	(682,505)
Purchases of property and equipment	(665)	(655)
Net cash provided by investing activities	400,852	235,656
Cash flows from financing activities
Proceeds from stock option exercises and employee stock purchase plan issuances	6,930	3,080
Payment of employee tax obligations related to vesting of restricted stock units	(641)	(39)
Net cash provided by financing activities	6,289	3,041
Net decrease in cash, cash equivalents and restricted cash	(13,925)	(94,407)
Cash, cash equivalents and restricted cash at beginning of period	163,969	295,502
Cash, cash equivalents and restricted cash at end of period	$ 150,044	201,095
Supplemental disclosure of non-cash operating activities
Purchases of property and equipment included in accounts payable		$ 54

Accrued Expenses (Tables)

9 Months Ended

Sep. 30, 2023

Payables and Accruals [Abstract]

Summary of Accrued Expenses

The following table summarizes accrued expenses as of September 30, 2023 and December 31, 2022:


	September 30,		December 31,
	2023		2022
	(in thousands)
Accrued research and development costs	$	63,386	$	32,565
Restructuring		24,250		—
Employee-related		14,108		29,372
Professional services		12,497		10,172
Other		660		557
	$	114,901	$	72,666

Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2023

Share-Based Payment Arrangement [Abstract]

Summary of Activity Relating to Restricted Stock Units

The following table summarizes activity relating to time-based restricted stock units and performance restricted stock units:


	Shares			Weighted Average Grant Date Fair Value
Outstanding as of December 31, 2022		1,415,481		$	48.73
Granted		2,594,486		$	30.55
Vested		(236,852	)	$	56.32
Forfeited		(484,311	)	$	43.37
Outstanding as of September 30, 2023		3,288,804		$	34.63

Summary of Activity Relating to Time Based and Performance Based Stock Options

The following table summarizes activity related to time-based and performance-based stock options:


	Shares			Weighted Average Exercise Price		Weighted Average Remaining Life (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding as of December 31, 2022		7,788,350		$	77.95		6.36	$	7,275
Granted		919,751		$	45.76
Exercised		(65,940	)	$	16.58
Forfeited		(510,199	)	$	56.31
Outstanding as of September 30, 2023		8,131,962		$	76.17		5.91	$	371
Exercisable as of September 30, 2023		5,934,180		$	82.73		5.00	$	370

Summary of Stock-Based Compensation Expense Recognized

The following table summarizes stock-based compensation expense recognized during the three and nine months ended September 30, 2023 and 2022:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
	(in thousands)
Research and development	$	6,874	$	5,964	$	20,143	$	21,037
Selling, general and administrative		20,979		7,205		39,441		25,321
Restructuring		838		—		838		—
	$	28,691	$	13,169	$	60,422	$	46,358

Summary of Stock-Based Compensation Expense by Award Type

The following table summarizes stock-based compensation expense by award type recognized during the three and nine months ended September 30, 2023 and 2022:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
	(in thousands)
Stock options	$	20,251	$	11,992	$	39,929	$	40,659
Restricted stock units		8,101		730		19,272		4,982
Employee stock purchase plan		339		447		1,221		717
	$	28,691	$	13,169	$	60,422	$	46,358

Fair Value Measurements - Summary of Gross Unrealized Gains and Losses of Marketable Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 731,075	$ 1,120,000
Gross Unrealized Gains	2	44
Gross Unrealized Losses	(3,737)	(10,250)
Fair Value	727,340	1,109,794
U.S. Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	203,722	307,173
Gross Unrealized Gains	1
Gross Unrealized Losses	(1,100)	(4,262)
Fair Value	202,623	302,911
U.S. Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	179,873	358,019
Gross Unrealized Gains		6
Gross Unrealized Losses	(1,303)	(3,530)
Fair Value	178,570	354,495
International Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	71,351	128,374
Gross Unrealized Gains		7
Gross Unrealized Losses	(440)	(1,133)
Fair Value	70,911	127,248
U.S. Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	34,144	63,234
Gross Unrealized Losses	(26)	(120)
Fair Value	34,118	63,114
International Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	72,646	133,338
Gross Unrealized Losses	(92)	(175)
Fair Value	72,554	133,163
U.S. Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	10,217	15,613
Fair Value	10,217	15,613
U.S. Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	159,122	114,249
Gross Unrealized Gains	1	31
Gross Unrealized Losses	(776)	(1,030)
Fair Value	$ 158,347	$ 113,250

Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2023
Accounting Policies [Abstract]
Risks and Uncertainties	Risks and Uncertainties The Company is subject to risks and uncertainties common to companies in the biopharmaceutical industry, including, but not limited to, the risks associated with developing product candidates at each stage of non-clinical and clinical development; the challenges associated with gaining regulatory approval of such product candidates; the risks associated with the marketing and sale of pharmaceutical products; the potential for development by third parties of new technological innovations that may compete with the Company’s products and product candidates; the dependence on key personnel; the challenges of protecting proprietary technology; the need to comply with government regulations; the high costs of drug development; the uncertainty of being able to secure additional capital when needed to fund operations; and the direct or indirect impacts of the macroeconomic environment and geopolitical events on its development activities, operations and financial condition. The product candidates developed by the Company require approvals from the FDA or foreign regulatory agencies prior to commercial sales. There can be no assurance that the current and future product candidates of the Company will receive, or that the Company’s current products, ZULRESSO and ZURZUVAE, will maintain, the necessary approvals. If the Company fails to successfully complete clinical development and generate results sufficient to file for regulatory approval or is denied approval or approval is delayed for any of its product candidates, such occurrences may have a material adverse impact on the Company’s business and its financial condition. The Company is also subject to additional risks and uncertainties arising from changes to the macroeconomic environment and geopolitical events. U.S. and global financial markets have experienced volatility and disruption due to macroeconomic and geopolitical events such as rising inflation, the risk of a recession and ongoing conflicts in other countries. In addition, if equity and credit markets deteriorate, including as a result of past and potential future bank failures, it may make any future debt or equity financing more difficult to obtain on favorable terms, and potentially more dilutive to its existing stockholders. The Company cannot predict at this time to what extent it and its collaborators, employees, suppliers, contract manufacturers and/or vendors could potentially be negatively impacted by these events.
Going Concern	Going Concern Under Accounting Standards Update (“ASU”) No. 2014-15, Presentation of Financial Statements—Going Concern (Subtopic 205-40), the Company has the responsibility to evaluate whether conditions and/or events raise substantial doubt about its ability to meet its future financial obligations as they become due within one year after the date that the financial statements are issued. The Company has incurred losses and negative cash flows from operations in each year since its inception, except for net income of $606.1 million for the year ended December 31, 2020, reflecting revenue recognized under a collaboration and license agreement with Biogen (the “Biogen Collaboration Agreement”). As of September 30, 2023, the Company had an accumulated deficit of $2.5 billion. From its inception through September 30, 2023, the Company has received aggregate net proceeds of $2.8 billion from the sales of redeemable convertible preferred stock prior to its initial public offering (“IPO”), the issuance of convertible notes, and the sales of common stock in its IPO in July 2014, in follow-on public offerings, and to BIMA under a stock purchase agreement executed in connection with the Biogen Collaboration Agreement. The Company has also received $1.0 billion in upfront payments under its collaborations with Biogen and Shionogi & Co., Ltd. (“Shionogi”). Until such time, if ever, as the Company can generate substantial product revenue and/or collaboration revenue and achieve sustained profitability, the Company expects to finance its cash needs through a combination of equity offerings, debt financings, collaborations, strategic alliances, licensing arrangements and other sources of funding. If the Company is unable to raise additional funds through equity or debt financings or other sources of funding when needed, the Company may be required to delay, limit, reduce or terminate product development or future commercialization efforts or grant rights to develop and market products or product candidates that the Company would otherwise prefer to develop and market itself. The Company expects that, based on its current operating plans, the Company’s existing cash, cash equivalents and marketable securities will be sufficient to fund its currently planned operations for at least the next 12 months from the filing date of these unaudited interim condensed consolidated financial statements (“condensed consolidated financial statements”). At some point after that time, the Company anticipates it will require additional financing to fund its future operations. Even if the Company believes it has sufficient funds for its current or future operating plans, the Company may seek to raise additional capital if market conditions are favorable or in light of other strategic considerations.
Basis of Presentation	Basis of Presentation The condensed consolidated financial statements of the Company included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission. Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) have been condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements as of and for the year ended December 31, 2022, included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022. The condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements. In the opinion of the Company’s management, the accompanying condensed consolidated financial statements contain all adjustments, consisting of only normal recurring adjustments, necessary for a fair statement of its financial position as of September 30, 2023, its results of operations and comprehensive loss for the three and nine months ended September 30, 2023 and 2022, its cash flows for the nine months ended September 30, 2023 and 2022, and its statements of changes in stockholders’ equity for the three and nine months ended September 30, 2023 and 2022. The consolidated balance sheet at December 31, 2022 was derived from audited financial statements, but does not include all disclosures required by GAAP. The results for the three and nine months ended September 30, 2023 are not necessarily indicative of the results for the year ending December 31, 2023, or for any future period.
Principles of Consolidation	Principles of Consolidation The condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries as disclosed in Note 2, Summary of Significant Accounting Policies, within the “Notes to Consolidated Financial Statements” accompanying its Annual Report on Form 10-K for the year ended December 31, 2022. Intercompany accounts and transactions have been eliminated.
Use of Estimates	Use of Estimates The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting period.
Research and Development Costs and Accruals	Research and Development Costs and Accruals Research and development expenses are comprised of costs incurred in performing research and development activities, including salaries and benefits, overhead costs, depreciation, contract services and other related costs. Research and development costs are expensed to operations as the related obligation is incurred. The Company has entered into various research and development contracts with research institutions and other companies both inside and outside of the U.S. These agreements are generally cancelable, and related costs are recorded as research and development expenses as incurred. The Company records accruals for estimated ongoing research and development costs. When billing terms under these contracts do not coincide with the timing of when the work is performed, the Company is required to make estimates of outstanding obligations to those third parties as of the end of the reporting period. Any accrual estimates are based on a number of factors, including the Company’s knowledge of the progress towards completion of the research and development activities, invoicing to date under the contracts, communication from the research institution or other companies of any actual costs incurred during the period that have not yet been invoiced, and the costs included in the contracts. Significant judgments and estimates are made in determining the accrued balances at the end of any reporting period. Actual results could differ from the estimates made by the Company. The historical accrual estimates made by the Company have not been materially different from the actual costs.
Revenue Recognition	Revenue Recognition The Company generates revenue from the sale of ZULRESSO, which was approved by the FDA in March 2019 and the Company subsequently began selling in June 2019, and from collaboration and supply agreements with the Company’s collaborators. To date, revenue from collaboration agreements has come from initial, upfront payments allocated to licenses of intellectual property delivered to the Company’s collaborators and from the supply of material for clinical trials under a supply agreement. Under Accounting Standards Codification (“ASC”) Topic 606, Revenue from Contracts with Customers (“Topic 606”), an entity recognizes revenue when or as performance obligations are satisfied by transferring control of promised goods or services to a customer, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of Topic 606, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price, including variable consideration, if any; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. Arrangements that include rights to additional goods or services that are exercisable at a customer’s discretion are generally considered options. The Company assesses if these options provide a material right to the customer and if so, they are considered performance obligations. The exercise of a material right may be accounted for as a contract modification or as a continuation of the contract for accounting purposes. For contracts determined to be within the scope of Topic 606, the Company assesses whether the goods or services promised within each contract are distinct to identify those that are performance obligations. This assessment involves subjective determinations and requires management to make judgments about the individual promised goods or services and whether such are separable from the other aspects of the contractual relationship. Promised goods and services are considered distinct provided that: (i) the customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer and (ii) the entity’s promise to transfer the good or service to the customer is separately identifiable from other promises in the contract. The Company allocates the transaction price (the amount of consideration it expects to be entitled to from a customer in exchange for the promised goods or services) to each performance obligation and recognizes the associated revenue when (or as) each performance obligation is satisfied. The Company’s estimate of the transaction price for each contract includes all variable consideration to which the Company expects to be entitled. Collaboration and License Revenue In assessing whether a promised good or service is distinct in the evaluation of a collaboration or license arrangement subject to Topic 606, the Company considers factors such as the research, manufacturing and commercialization capabilities of the collaboration partner and the availability of the associated expertise in the general marketplace. The Company also considers the intended benefit of the contract in assessing whether a promised good or service is separately identifiable from other promises in the contract. If a promised good or service is not distinct, the Company is required to combine that good or service with other promised goods or services until it identifies a bundle of goods or services that is distinct. The transaction price is then determined and allocated to the identified performance obligations in proportion to their standalone selling prices (“SSP”) on a relative SSP basis. SSP is determined at contract inception and is not updated to reflect changes between contract inception and when the performance obligations are satisfied. Determining the SSP for performance obligations requires significant judgment. In developing the SSP for a performance obligation, the Company considers applicable market conditions and relevant entity-specific factors, including factors that were contemplated in negotiating the agreement with the customer and estimated costs. In certain circumstances, the Company may apply the residual method to determine the SSP of a good or service if the standalone selling price is considered highly variable or uncertain. The Company validates the SSP for performance obligations by evaluating whether changes in the key assumptions used to determine the SSP will have a significant effect on the allocation of arrangement consideration between multiple performance obligations. If the consideration promised in a contract includes a variable amount, the Company estimates the amount of consideration to which it will be entitled in exchange for transferring the promised goods or services to a customer. The Company determines the amount of variable consideration by using the expected value method or the most likely amount method. The Company includes the unconstrained amount of estimated variable consideration in the transaction price. The amount included in the transaction price is constrained to the amount for which it is probable that a significant reversal of cumulative revenue recognized will not occur. At the end of each subsequent reporting period, the Company re-evaluates the estimated variable consideration included in the transaction price and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis in the period of adjustment. If an arrangement includes development and regulatory milestone payments, the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company’s control or the licensee’s control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. In determining the transaction price, the Company adjusts consideration for the effects of the time value of money if the timing of payments provides the Company with a significant benefit of financing. The Company does not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between payment by the licensees and the transfer of the promised goods or services to the licensees will be one year or less. The Company assessed its arrangements with Shionogi and Biogen and concluded that a significant financing component does not exist for either arrangement. For arrangements with licenses of intellectual property that include sales-based royalties or milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties or milestone payments relate, the Company recognizes royalty revenue and sales-based milestones at the later of (i) when the related sales occur, or (ii) when the performance obligation to which the royalty or milestone payment has been allocated has been satisfied. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) each performance obligation is satisfied at a point in time or over time, and if over time this is based on the use of an output or input method. Revenue from the Company’s collaboration agreement with Shionogi has come from initial, upfront consideration upon execution of the agreement and for the supply of drug product for Shionogi’s clinical trials. Revenue from the Company’s collaboration agreement with Biogen has come from initial, upfront consideration related to the execution of the Biogen Collaboration Agreement. For additional information, refer to Note 6, Collaboration Agreements. Product Revenue, Net The Company recognizes product revenue, net of variable consideration related to certain allowances and accruals that are determined using the expected value method, in its condensed consolidated financial statements at the point in time when control transfers to the customer, which is typically when the product has been delivered to the customer’s location. The amount included in the transaction price is constrained to the amount for which it is probable that a significant reversal of cumulative revenue recognized will not occur. The Company’s only performance obligation identified for ZULRESSO is to deliver the product to the location specified by the customer’s order. The Company records shipping and handling costs associated with delivery of product to its customers within selling, general and administrative expenses on its condensed consolidated statements of operations and comprehensive loss. The Company expenses incremental costs of obtaining a contract as incurred if the expected amortization period of the asset would be less than one year. If the Company were to incur incremental costs with an amortization period greater than a year, such costs would be capitalized as contract assets, as they are expected to be recovered, and would be expensed by amortizing on a systematic basis that is consistent with the transfer to the customer of the goods or services to which the asset relates. The Company did not have any contract assets (unbilled receivables) at September 30, 2023, as customer invoicing generally occurs before or at the time of revenue recognition. The Company did not have any contract liabilities at September 30, 2023 related to its sales of ZULRESSO, as the Company did not receive any payments in advance of satisfying its performance obligations to its customers. Amounts billed or invoiced that are considered trade accounts receivable are included in prepaid expenses and other current assets on the condensed consolidated balance sheets. As of September 30, 2023 and December 31, 2022, the Company had not provided any allowance for bad debts against the trade accounts receivable, and the amount of trade accounts receivable was not significant. The Company records reserves, based on contractual terms, for the following components of variable consideration related to product sold during the reporting period, as well as its estimate of product that remains in the distribution channel inventory of its customers at the end of the reporting period. On a quarterly basis, the Company updates its estimates, if necessary, and records any material adjustments in the period they are identified. Chargebacks: The Company estimates chargebacks from its customers who directly purchase the product from the Company for discounts resulting from contractual commitments to sell products to eligible healthcare settings at prices lower than the list prices charged to its customers. Customers charge the Company for the difference between what they pay to the Company for the product and the selling price to the eligible healthcare settings. Reserves for chargebacks consist of credits that the Company expects to issue for units that remain in the distribution channel inventories at the end of each reporting period that the Company expects will be sold to eligible healthcare settings, and chargebacks that customers have claimed, but for which the Company has not yet issued a credit. Government Rebates: The Company is subject to discount obligations under government programs, including Medicaid. The Company records reserves for rebates in the same period the related product revenue is recognized, resulting in a reduction of ZULRESSO product revenue and a current liability that is included in accrued expenses on its condensed consolidated balance sheets. The Company’s liability for these rebates consists of invoices received for claims from prior quarters that have not been paid or for which an invoice has not yet been received, estimates of claims for the current quarter, and estimates of future claims that will be made for product that has been recognized as revenue, but which remains in the distribution channel at the end of each reporting period. Trade Discounts and Allowances: The Company generally provides customary invoice discounts on ZULRESSO sales to its customers for prompt payment and the Company pays fees for sales order management, data, and distribution services. The Company estimates its customers will earn these discounts and fees and deducts these discounts and fees in full from gross ZULRESSO revenue and accounts receivable at the time the Company recognizes the related revenue. Financial Assistance: The Company provides voluntary financial assistance programs to patients with commercial insurance that have coverage and reside in states that allow financial assistance. The Company estimates the financial assistance amounts for ZULRESSO and records any such amounts within accrued expenses on its condensed consolidated balance sheets. The calculation of the accrual for financial assistance is based on an estimate of claims and the cost per claim that the Company expects to receive using demographics for patients who have registered and been approved for assistance. Any adjustments are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability, which is included as a component of accrued expenses on the condensed consolidated balance sheets. Product Returns: Consistent with industry practice, the Company offers product return rights to customers for damaged, defective or expiring product, provided it is within a specified period around the product expiration date as set forth in the Company’s return goods policy. The Company estimates the amount of its product sales that may be returned by its customers and records this estimate as a reduction of revenue in the period the related product revenue is recognized, as well as a reserve within accrued expenses on the condensed consolidated balance sheets. Product returns have not been significant to date and are not expected to be significant in the future.
Collaborative Arrangements	Collaborative Arrangements The Company analyzes its collaboration arrangements to assess whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities and therefore within the scope of ASC Topic 808, Collaborative Arrangements (“Topic 808”). This assessment is performed throughout the life of the arrangement based on changes in the responsibilities of all parties in the arrangement. For collaboration arrangements within the scope of Topic 808 that contain multiple elements, the Company first determines which elements of the collaboration are deemed to be within the scope of Topic 808 and which elements of the collaboration are more reflective of a vendor-customer relationship and therefore within the scope of Topic 606. For elements of collaboration arrangements that are accounted for pursuant to Topic 808, an appropriate recognition method is determined and applied consistently, either by analogy to authoritative accounting literature or by applying a reasonable and rational policy election. For those elements of the arrangement that are accounted for pursuant to Topic 606, the Company applies the five-step model described above, and presents the arrangement as collaboration revenue in the condensed consolidated statements of operations and comprehensive loss. For collaboration arrangements that are within the scope of Topic 808, the Company evaluates the income statement classification for presentation of amounts due from or owed to other participants associated with multiple activities in a collaboration arrangement based on the nature of each separate activity. Payments or reimbursements that are the result of a collaborative relationship instead of a customer relationship, such as co-development and co-commercialization activities, are recorded as research and development expense or selling, general and administrative expense, in the event of a payment to the collaborative partner in a period, or a reduction to these expense line items in the event of a reimbursement from the collaboration partner in a period, as appropriate.
Fair Value Measurements	Fair Value Measurements Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Financial assets and liabilities carried at fair value are classified and disclosed in one of the following three categories: Level 1 — Quoted market prices in active markets for identical assets or liabilities. Level 2 — Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The Company’s cash equivalents and marketable securities at September 30, 2023 and December 31, 2022 were carried at fair value, determined according to the fair value hierarchy; see Note 3, Fair Value Measurements. The carrying amounts reflected in the condensed consolidated balance sheets for the collaboration receivable – related party, accounts payable and accrued expenses approximate their fair values due to their short-term maturities at September 30, 2023 and December 31, 2022, respectively.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements Accounting standards that have been issued or proposed by the Financial Accounting Standards Board or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s condensed consolidated financial statements upon adoption.

Fair Value Measurements - Summary of Company's Cash Equivalents and Marketable Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	$ 147,747	$ 161,185
Total marketable securities	727,340	1,109,794
Total cash equivalents and marketable securities	875,087	1,270,979
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	139,770	161,185
Total cash equivalents and marketable securities	139,770	161,185
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	7,977
Total marketable securities	727,340	1,109,794
Total cash equivalents and marketable securities	735,317	1,109,794
Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	139,770	161,185
Money Market Funds [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	139,770	161,185
International Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	70,911	127,248
International Corporate Bonds [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	70,911	127,248
U.S. Government Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	202,623	302,911
U.S. Government Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	202,623	302,911
U.S. Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	4,993
Total marketable securities	178,570	354,495
U.S. Corporate Bonds [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	4,993
Total marketable securities	178,570	354,495
U.S. Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	2,984
Total marketable securities	34,118	63,114
U.S. Commercial Paper [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	2,984
Total marketable securities	34,118	63,114
International Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	72,554	133,163
International Commercial Paper [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	72,554	133,163
U.S. Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	10,217	15,613
U.S. Certificates of Deposit [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	10,217	15,613
U.S. Municipal Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	158,347	113,250
U.S. Municipal Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	$ 158,347	$ 113,250

Restructuring - Schedule of Restructuring Accrual (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023
Restructuring Reserve [Roll Forward]
Restructuring accrual, Balance as of July 1, 2023	$ 0
Restructuring expenses incurred	33,599	$ 33,599
Cash paid	(5,715)
Non-cash activity	(3,634)
Restructuring accrual, Balance as of September 30, 2023	$ 24,250	$ 24,250

Fair Value Measurements - Additional Information (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Debt Instrument Fair Value Carrying Value [Line Items]
Transfers among the Level 1, Level 2 and Level 3 categories	$ 0		$ 0
Impairment of assets	0	$ 0
US Treasury Bond Securities \| Corporate Bonds and Municipal Securities [Member]
Debt Instrument Fair Value Carrying Value [Line Items]
Marketable securities fair value held to maturity	$ 82,300,000	$ 211,200,000
Maximum [Member] \| US Treasury Bond Securities \| U.S. Corporate Bonds [Member]
Debt Instrument Fair Value Carrying Value [Line Items]
Marketable securities, remaining contractual maturities	1 year	1 year
Maximum [Member] \| US Treasury Bond Securities \| Corporate Bonds and Municipal Securities [Member]
Debt Instrument Fair Value Carrying Value [Line Items]
Marketable securities held, maturity period	2 years	2 years
Minimum [Member] \| US Treasury Bond Securities \| Corporate Bonds and Municipal Securities [Member]
Debt Instrument Fair Value Carrying Value [Line Items]
Marketable securities held, maturity period	1 year	1 year

Collaboration Agreements - Summary of Operating Expenses Category Related to Collaboration Agreement (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Net reimbursement to (from) Biogen reflected in the condensed consolidated statements of operations and comprehensive loss:
Total operating costs and expenses	$ 214,565	$ 143,219	$ 546,258	$ 397,908
Biogen Collaboration Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Expenses related to the Biogen Collaboration Agreement incurred by Sage	83,276	53,139	210,936	161,111
Net reimbursement to (from) Biogen reflected in the condensed consolidated statements of operations and comprehensive loss:
Selling, general and administrative expenses	5,835	(480)	16,345	(4,788)
Operating expenses	(22,369)	(18,347)	(51,558)	(62,152)
Total operating costs and expenses	60,907	34,792	159,378	98,959
Research and Development [Member] \| Biogen Collaboration Agreement [Member]
Net reimbursement to (from) Biogen reflected in the condensed consolidated statements of operations and comprehensive loss:
Research and development expenses	$ (28,204)	$ (17,867)	$ (67,903)	$ (57,364)

Restructuring - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	9 Months Ended
	Aug. 31, 2023	Sep. 30, 2023	Sep. 30, 2023
Restructuring Costs [Abstract]
Percentage of workforce eliminated	40.00%
Restructuring expense		$ 33.6
Restructuring charges expected to be incurred			$ 36.9
Restructuring expense to be recorded in future periods		$ 3.3	$ 3.3

Restructuring (Tables)

9 Months Ended

Sep. 30, 2023

Restructuring and Related Activities [Abstract]

Schedule of Restructuring Accrual

The following table summarizes activity related to the restructuring accrual:


	Restructuring accrual
	(in thousands)
Balance as of July 1, 2023	$	-
Restructuring expenses incurred		33,599
Cash paid		(5,715	)
Non-cash activity		(3,634	)
Balance as of September 30, 2023	$	24,250

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Total revenue	$ 2,716	$ 1,739	$ 8,483	$ 4,821
Operating costs and expenses:
Cost of goods sold	905	184	1,339	670
Research and development	101,919	81,553	291,905	236,868
Selling, general and administrative	78,142	61,482	219,415	160,370
Restructuring	33,599		33,599
Total operating costs and expenses	214,565	143,219	546,258	397,908
Loss from operations	(211,849)	(141,480)	(537,775)	(393,087)
Interest income, net	10,274	4,127	29,276	7,397
Other income (expense), net	(55)	30	(284)	52
Net loss	$ (201,630)	$ (137,323)	$ (508,783)	$ (385,638)
Net loss per share - basic	$ (3.37)	$ (2.31)	$ (8.51)	$ (6.51)
Net loss per share - diluted	$ (3.37)	$ (2.31)	$ (8.51)	$ (6.51)
Weighted average number of common shares outstanding— basic	59,912,378	59,428,123	59,786,254	59,242,563
Weighted average number of common shares outstanding— diluted	59,912,378	59,428,123	59,786,254	59,242,563
Comprehensive loss:
Net loss	$ (201,630)	$ (137,323)	$ (508,783)	$ (385,638)
Other comprehensive items:
Unrealized gain (loss) on marketable securities	1,909	(1,011)	6,471	(12,223)
Total other comprehensive gain (loss)	1,909	(1,011)	6,471	(12,223)
Total comprehensive loss	(199,721)	(138,334)	(502,312)	(397,861)
Product Revenue [Member]
Total revenue	$ 2,716	$ 1,739	8,469	$ 4,821
Collaboration Revenue [Member]
Total revenue			$ 14

Stock-Based Compensation - Summary of Stock-Based Compensation Expense by Award Type (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total Stock-based compensation expense	$ 28,691	$ 13,169	$ 60,422	$ 46,358
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total Stock-based compensation expense	20,251	11,992	39,929	40,659
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total Stock-based compensation expense	8,101	730	19,272	4,982
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total Stock-based compensation expense	$ 339	$ 447	$ 1,221	$ 717

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Collaboration Agreements

9 Months Ended

Sep. 30, 2023

Shionogi Collaboration Agreement [Member]

Collaboration Agreements

Shionogi

In June 2018, the Company entered into a strategic collaboration with Shionogi for the clinical development and commercialization of zuranolone for the treatment of MDD and other potential indications in Japan, Taiwan and South Korea (the “Shionogi Territory”). In October 2018, the Company entered into a supply agreement with Shionogi for the Company to supply zuranolone clinical material to Shionogi.

Under the terms of the collaboration agreement, Shionogi is responsible for all clinical development and regulatory filings for zuranolone in MDD and other indications in the Shionogi Territory and would be responsible for commercialization of zuranolone in the Shionogi Territory, if zuranolone is successfully developed and obtains marketing approval in any of the countries within the Shionogi Territory. Shionogi was required to make an upfront payment to the Company of $90.0 million, and the Company will be eligible to receive additional payments of up to $485.0 million if certain regulatory and commercial milestones are achieved by Shionogi. The potential future milestone payments include up to $70.0 million for the achievement of specified regulatory milestones, up to $30.0 million for the achievement of specified commercialization milestones, and up to $385.0 million for the achievement of specified net sales milestones. The Company is eligible to receive tiered royalties on sales of zuranolone in the Shionogi Territory, if development efforts are successful, with tiers averaging in the low to mid-twenty percent range, subject to other terms of the agreement. Shionogi has also granted to the Company certain rights to co-promote zuranolone in Japan. As between the Company and Shionogi, the Company maintains exclusive rights to develop and commercialize zuranolone outside of the Shionogi Territory. The upfront cash payment and any payments for milestones and royalties are non-refundable and non-creditable. Due to the uncertainty of pharmaceutical development and the high historical failure rates generally associated with drug development, the Company may not receive any milestone payments or any royalty payments from Shionogi.

The Company concluded that Shionogi meets the definition of a customer because the Company is delivering intellectual property and know-how rights for the zuranolone program in support of territories in which the parties are not jointly sharing the risks and rewards. In addition, the Company determined that the Shionogi collaboration met the requirements to be accounted for as a contract, including that it was probable that the Company will collect the consideration to which the Company was entitled in exchange for the goods or services that will be delivered to Shionogi.

The Company determined that the performance obligations in the Shionogi collaboration agreement included the license to zuranolone and the supply of certain materials during the clinical development phase, which includes the supply of active pharmaceutical ingredient (“API”). The performance obligation related to the license to zuranolone was determined to be distinct from other performance obligations and therefore was a separate performance obligation for which control was transferred upon signing. The obligation to provide certain clinical materials, including API for use during the development period, was determined to be a separate performance obligation. Given that Shionogi is not obligated to purchase any minimum amount or quantities of commercial API, the supply of API to Shionogi for

commercial use was determined to be an option for Shionogi, rather than a performance obligation of the Company at contract inception and will be accounted for if and when exercised. The Company also determined that there was no separate material right in connection with the supply of API for commercial use as the expected pricing was not at a discount. Given this fact pattern, the Company has concluded the agreement has two performance obligations.

Under the clinical supply agreement, the Company is obligated to manufacture and supply to Shionogi (i) clinical quantities of API reasonably required by Shionogi for the development of licensed products in the Shionogi territory under the collaboration and license agreement and (ii) quantities of drug product reasonably required for use by Shionogi in Phase 1 clinical trials of zuranolone in the Shionogi territory under the collaboration and license agreement, in the quantities agreed to by the parties. Collaboration revenue from the clinical supply agreement, which excludes the $90.0 million upfront payment, pertains to the clinical material sold under the terms of the clinical supply agreement. The Company records the costs related to the clinical supply agreement in research and development expense on its condensed consolidated statements of operations and comprehensive loss. For the nine months ended September 30, 2023, the Company recognized $14,000 of collaboration revenue from the Company’s agreement with Shionogi. For the nine months ended September 30, 2022, the Company recognized no collaboration revenue from the Company’s agreement with Shionogi.

The Company completed the evaluation of the standalone selling prices of each of the performance obligations and determined that the standalone selling price of the license performance obligation was $90.0 million. The Company recognized the transaction price allocated to the license performance obligation of $90.0 million as revenue during the quarter upon delivery of the license to Shionogi and resulting ability of Shionogi to use and benefit from the license, which was in the three months ended June 30, 2018. The remaining transaction price related to the performance obligation for the supply of certain clinical material is not significant. The potential milestone payments that the Company is eligible to receive were excluded from the transaction price, as all milestone amounts were fully constrained based on the probability of achievement. The Company will re-evaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur, and, if necessary, adjust its estimate of the transaction price.

Biogen

In November 2020, the Company entered into the Biogen Collaboration Agreement to jointly develop and commercialize SAGE-217 products for the treatment of MDD, PPD and other disorders and SAGE-324 products for essential tremor and other disorders. Concurrently, the Company also entered into a stock purchase agreement with BIMA (the “Biogen Stock Purchase Agreement”) under which BIMA purchased shares of the Company’s common stock. The Biogen Collaboration Agreement became effective on December 28, 2020 (the “Effective Date”).

Under the terms of the Biogen Collaboration Agreement, the Company granted Biogen co-exclusive licenses to develop and commercialize SAGE-217 products and SAGE-324 products (each, a “Product Class” and together, the “Licensed Products”) in the U.S., an exclusive license to develop and commercialize SAGE-217 products in all countries of the world other than the U.S. and the Shionogi Territory, and an exclusive license to develop and commercialize SAGE-324 products in all countries of the world other than the U.S. The Company refers to the territories outside the U.S. to which Biogen has rights under the Biogen Collaboration Agreement with respect to the applicable Licensed Product as the “Biogen Territory”.

In connection with the effectiveness of the Biogen Collaboration Agreement and the closing of the sale of shares to BIMA in December 2020, the Company received $1.5 billion in consideration, comprised of an upfront payment of $875.0 million and the $650.0 million purchase price for 6,241,473 newly issued shares of the Company’s common stock (the “Biogen Shares”). As a result of the purchase of the Biogen Shares, Biogen has become a related party of the Company.

The Company is eligible to receive additional payments of up to $1.6 billion from Biogen if certain regulatory and commercial milestones are achieved. The potential future milestone payments for SAGE-217 products include up to $475.0 million for the achievement of specified regulatory and commercial milestones, including a milestone payment of $75.0 million for the first commercial sale of ZURZUVAE for the treatment of women with PPD in the U.S. and, if approved, a milestone payment of $150.0 million for the first commercial sale of ZURZUVAE for the treatment of MDD

in the U.S., and up to $300.0 million for the achievement of specified net sales milestones. The potential future milestone payments for SAGE-324 products include up to $520.0 million for the achievement of specified regulatory and commercial milestones and up to $300.0 million for the achievement of specified net sales milestones. The Company is also eligible to receive tiered royalties on net sales of SAGE-217 products and SAGE-324 products in the Biogen Territory at percentage rates ranging from the high teens to low twenties.

Due to the uncertainty of pharmaceutical development and the high historical failure rates generally associated with drug development, and the challenges of launching and commercializing a product, if approved, the Company may never receive any milestone payments or any royalty payments under the Biogen Collaboration Agreement.

Development and commercialization activities in the U.S. are conducted pursuant to plans agreed to by the Company and Biogen and overseen by a joint steering committee that will consist at all times of an equal number of representatives of each party. The Company and Biogen will share equally in the costs for development and commercialization, as well as the profits and losses upon FDA approval and commencement of product sales, in the U.S., subject to the Company’s opt-out right described below. Biogen will be solely responsible for all development activities and costs related to any development and commercialization of SAGE-217 products and SAGE-324 products for the Biogen Territory, and the Company will receive royalties on any sales in the Biogen Territory, as mentioned above. Biogen will be the principal and record sales of SAGE-217 products globally. The Company will be the principal and record sales of SAGE-324 products in the U.S. and Biogen will be the principal and record sales of SAGE-324 products in the Biogen Territory.

The Company will supply API and bulk drug product for the Biogen Territory and API, bulk drug product and final drug product for the U.S. to support development and commercialization activities. Biogen has the right to assume manufacturing responsibilities for API for the Biogen Territory at any time during the term of the agreement and will, within a reasonable period of time after the Effective Date, assume manufacturing responsibility for bulk drug product for the Biogen Territory.

Unless terminated earlier, the Biogen Collaboration Agreement will continue on a Licensed Product-by-Licensed Product and country-by-country basis until the date on which (a) in any country in the Biogen Territory, the royalty term has expired for all Licensed Products in a Product Class in such country, and (b) for the U.S., the parties agree to permanently cease to commercialize all Licensed Products in a Product Class. Biogen also has the right to terminate the Biogen Collaboration Agreement for convenience in its entirety, on a Product Class-by-Product Class basis or as to a particular region, upon advance written notice. The Company has an opt-out right to convert the co-exclusive licenses in the U.S. to an exclusive license to Biogen on a Product Class-by-Product Class basis. Following the exercise of the opt-out right, the Company would no longer share equally in the profits and losses in the U.S. and would be entitled to receive certain royalty payments at percentage rates ranging from the high teens to low twenties and additional sales milestones.

The Company concluded that the Biogen Collaboration Agreement and the Biogen Stock Purchase Agreement should be combined and treated as a single arrangement for accounting purposes as the agreements were entered into contemporaneously and in contemplation of one another. The Company determined that the combined agreements had elements that were within the scope of Topic 606 and Topic 808.

As of the Effective Date, the Company identified the following promises in the Biogen Collaboration Agreement that were evaluated under the scope of Topic 606: delivery of (i) a co-exclusive license for SAGE-217 products in the U.S.; (ii) an exclusive license for SAGE-217 products in the Biogen Territory; (iii) a co-exclusive license for SAGE-324 products in the U.S.; (iv) an exclusive license for SAGE-324 products in the Biogen Territory; (v) the clinical manufacturing supply of API and bulk drug product for SAGE-217 products in the Biogen Territory; and (vi) the clinical manufacturing supply of API and bulk drug product for SAGE-324 products in the Biogen Territory.

The Company also evaluated whether certain options outlined within the Biogen Collaboration Agreement represented material rights that would give rise to a performance obligation and concluded that none of the options convey a material right to Biogen and therefore are not considered separate performance obligations within the Biogen Collaboration Agreement.

The Company assessed the above promises and determined that the co-exclusive licenses for SAGE-217 products and SAGE-324 products in the U.S. are reflective of a vendor-customer relationship and therefore represent performance obligations within the scope of Topic 606. The co-exclusive license for SAGE-217 products and SAGE-324 products in the U.S. are considered functional intellectual property and distinct from other promises under the contract. The exclusive licenses for SAGE-217 products and SAGE-324 products in the Biogen Territory are considered functional licenses that are distinct in the context of the Biogen Collaboration Agreement as Biogen can benefit from the licenses on its own or together with other readily available resources. As the co-exclusive licenses in the U.S. and the exclusive licenses in the Biogen Territory are delivered at the same time, they are considered one performance obligation at contract inception. The clinical manufacturing supply of API and bulk drug product for SAGE-217 products and SAGE-324 products for the Biogen Territory are considered distinct in the context of the Biogen Collaboration Agreement as Biogen can benefit from the manufacturing services together with the licenses transferred by the Company at the inception of the agreement. Therefore, each represents a separate performance obligation within a contract with a customer under the scope of Topic 606 at contract inception.

The Company considers the collaborative activities associated with the co-development, co-commercialization, and co-manufacturing of SAGE-217 products and SAGE-324 products in the U.S. to be separate units of account within the scope of Topic 808 as the Company and Biogen are both active participants in the development and commercialization activities and are exposed to significant risks and rewards that are dependent on the development and commercial success of the activities in the arrangement. During the nine months ended September 30, 2023 and 2022, no collaboration revenue – related party was recognized related to the Biogen Collaboration Agreement.

In periods prior to commercialization, payments to or reimbursements from Biogen related to the co-development, co-commercialization, and co-manufacturing activities and the agreement of the parties to share equally the cost of these activities will be accounted for as an increase to or reduction of research and development expenses or selling, general and administrative expenses, depending on the nature of the activity.

During the three and nine months ended September 30, 2023, the Company recorded a net reimbursement of $22.4 million and $51.6 million, respectively, for the amounts due from Biogen as a reduction of or an addition to the related operating expense categories in the condensed consolidated statements of operations and comprehensive loss. During the three and nine months ended September 30, 2022, the Company recorded a net reimbursement of $18.3 million and $62.2 million, respectively, for the amounts due from Biogen as a reduction of the related operating expense categories in the condensed consolidated statements of operations and comprehensive loss.

As of September 30, 2023, the Company recorded a Collaboration Receivable – Related Party of $22.5 million in the condensed consolidated balance sheet for the amounts due for the three months ended September 30, 2023. During the nine months ended September 30, 2023, the Company received $42.7 million from Biogen for the amounts due for the three months ended December 31, 2022 and the six months ended June 30, 2023 and the Company made no payments to Biogen.


	Three Months Ended September 30,						Nine Months Ended September 30,
	2023			2022			2023			2022
	(in thousands)
Expenses related to the Biogen Collaboration Agreement incurred by Sage	$	83,276		$	53,139		$	210,936		$	161,111
Net reimbursement to (from) Biogen reflected in the condensed consolidated statements of operations and comprehensive loss:
Research and development expenses		(28,204	)		(17,867	)		(67,903	)		(57,364	)
Selling, general and administrative expenses		5,835			(480	)		16,345			(4,788	)
		(22,369	)		(18,347	)		(51,558	)		(62,152	)
Total net expenses related to the Biogen Collaboration Agreement in the condensed consolidated statements of operations and comprehensive loss	$	60,907		$	34,792		$	159,378		$	98,959

The Company determined the transaction price under Topic 606 at the inception of the Biogen Collaboration Agreement to be $1.1 billion, consisting of the upfront payment of $875.0 million plus $232.5 million in excess proceeds from the equity investment under the Biogen Stock Purchase Agreement, when measured at fair value, plus future variable consideration for manufacturing supply of clinical API and bulk drug product for the Biogen Territory. The amount of variable consideration related to the future manufacturing services was not material. The Company determined that any variable consideration related to clinical development and regulatory milestones is deemed to be fully constrained and therefore excluded from the transaction price due to the high degree of uncertainty and risk associated with these potential payments, as the Company determined that it could not assert that it was probable that a significant reversal in the amount of cumulative revenue recognized will not occur. The Company also determined that royalties and sales milestones relate solely to the licenses of intellectual property and are therefore excluded from the transaction price under the sales- or usage-based royalty exception of Topic 606. Revenue related to these royalties and sales milestones will only be recognized when the associated sales occur, and relevant thresholds are met.

As noted above, the Company identified three performance obligations in the Biogen Collaboration Agreement: (i) the delivery of the co-exclusive licenses for SAGE-217 products and SAGE-324 products in the U.S. and the exclusive licenses for SAGE-217 products and SAGE-324 products in the Biogen Territory; (ii) the clinical manufacturing supply of API and bulk drug product for SAGE-217 products in the Biogen Territory; and (iii) the clinical manufacturing supply of the API and bulk drug product for SAGE-324 products in the Biogen Territory. The selling price of each performance obligation in the Biogen Collaboration Agreement was determined based on the Company’s SSP with the objective of determining the price at which it would sell such an item if it were to be sold regularly on a standalone basis. The Company allocated the variable consideration related to the manufacturing obligations to the future clinical supply of SAGE-217 products and SAGE 324 products in the Biogen Territory and the remaining fixed consideration to the license obligation. The variable consideration related to the manufacturing obligations was not material. As such, the entirety of the $1.1 billion fixed consideration of the transaction price has been allocated to the transfer of the co-exclusive licenses for SAGE-217 products and SAGE-324 products in the U.S. and the exclusive licenses for SAGE-217 products and SAGE-324 products in the Biogen Territory. The Company recognizes revenue for the license performance obligations at a point in time, that is upon transfer of the licenses to Biogen. As control of these licenses was transferred on the Effective Date and Biogen could begin to use and benefit from the licenses, the Company recognized $1.1 billion of license revenue during the year ended December 31, 2020 under the Biogen Collaboration Agreement. The Company will recognize

revenue for the clinical manufacturing supply obligations at a point in time, that is upon the delivery of the supply to Biogen.

Accounting for the Biogen Stock Purchase Agreement

In connection with the execution of the Biogen Collaboration Agreement, the Company and BIMA entered into the Biogen Stock Purchase Agreement. Pursuant to the Biogen Stock Purchase Agreement, the Company sold the Biogen Shares to BIMA at a price of approximately $104.14 per share, which represented a 40 percent premium over the 30-day volume-weighted average share price as of the last trading day prior to the date the Biogen Collaboration Agreement and Biogen Stock Purchase Agreement were executed in November 2020, for aggregate consideration of $650.0 million. The sale of the shares to BIMA closed on December 31, 2020.

The Biogen Stock Purchase Agreement includes certain standstill provisions, lock-up restrictions, and a voting agreement with respect to the Biogen Shares. Pursuant to the terms of the Biogen Stock Purchase Agreement, BIMA has agreed not to, and to cause its affiliates not to, directly or indirectly acquire the Company’s securities, seek or propose a tender or exchange offer or merger between the Company and Biogen, solicit proxies or consents with respect to any matter, or undertake other specified actions, in each case subject to specified conditions. The standstill restrictions terminate on the earliest of (i) a specified regulatory milestone under the Biogen Collaboration Agreement, (ii) the date one year following the termination of the Biogen Collaboration Agreement and (iii) the seventh anniversary of the Effective Date. BIMA also agreed not to, and to cause its affiliates not to, sell or transfer any of the Biogen Shares for a period of eighteen months from the closing of the sale of the Biogen Shares, which period expired on June 30, 2022, and to limit sales and transfers of the Biogen Shares for an additional eighteen-month period, which expires December 31, 2023, in each case subject to specified conditions and exceptions.

The Company determined the fair value of the common shares issued using an option pricing valuation model to take into consideration the holding period restrictions. The fair value of the Company’s common stock was considered a Level 2 fair value measurement within the fair value hierarchy. The most significant assumptions within the model are the Company’s stock price, the term of the restrictions and the stock price volatility, which is based upon a blend of historical and implied volatility of the Company’s stock. Based on the fair value adjustments made by management, the fair value of the shares issued was determined to be $417.5 million, which was $232.5 million less than the proceeds received from BIMA for the issuance of the Company’s common stock under the Biogen Stock Purchase Agreement. As such, the $232.5 million in excess proceeds has been included in the $1.1 billion transaction price of the Biogen Collaboration Agreement determined above.

Collaboration Agreements - Additional Information (Detail) - USD ($)			3 Months Ended				6 Months Ended	9 Months Ended		12 Months Ended
	Nov. 30, 2020	Jun. 30, 2018	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2018	Jun. 30, 2023	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2020	Jun. 12, 2018
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue			$ 2,716,000		$ 1,739,000			$ 8,483,000	$ 4,821,000
Collaboration receivable - related party			22,513,000	$ 13,660,000				22,513,000
Collaboration Revenue [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue								14,000
Shionogi Collaboration Agreement [Member] \| Collaboration Revenue [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue								14,000,000	0
Shionogi Collaboration Agreement [Member] \| SAGE-217 [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment		$ 90,000,000.0
Average percentage on tiered royalties		20.00%
Revenue						$ 90,000,000.0
Standalone selling price of license performance obligation		$ 90,000,000.0				90,000,000.0
Shionogi Collaboration Agreement [Member] \| SAGE-217 [Member] \| Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Additional milestone payment receivable		485,000,000.0				$ 485,000,000.0
Shionogi Collaboration Agreement [Member] \| SAGE-217 [Member] \| Maximum [Member] \| Regulatory Milestones [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Future milestone payments		70,000,000.0
Shionogi Collaboration Agreement [Member] \| SAGE-217 [Member] \| Maximum [Member] \| Commercial Milestones [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Future milestone payments		30,000,000.0
Shionogi Collaboration Agreement [Member] \| SAGE-217 [Member] \| Maximum [Member] \| Sales Milestones [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Future milestone payments		$ 385,000,000.0
Biogen Collaboration Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration agreement effective date	Dec. 28, 2020
Upfront payment										$ 875,000,000.0
Revenue								0	0	1,100,000,000
Standalone selling price of license performance obligation										1,100,000,000
Sale of stock, consideration received										$ 1,500,000,000
Public offering of common stock, net of offering costs, Shares										6,241,473
Purchase price										$ 650,000,000.0
Operating expenses			22,400,000		$ 18,300,000			51,600,000	$ 62,200,000
Payments to related parties								0
Proceeds from related parties				$ 42,700,000			$ 42,700,000
Biogen Collaboration Agreement [Member] \| Related Party [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration receivable - related party			$ 22,500,000					$ 22,500,000
Biogen Collaboration Agreement [Member] \| SAGE-217 [Member] \| Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Additional milestone payment receivable											$ 1,600,000,000
Biogen Collaboration Agreement [Member] \| SAGE-217 [Member] \| Maximum [Member] \| First Commercial Sale of Zurzuvae for Treatment of MDD [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Future milestone payments	$ 150,000,000
Biogen Collaboration Agreement [Member] \| SAGE-217 [Member] \| Maximum [Member] \| First Commercial Sale Of Zurzuvae For Treatment Of Women With Ppd [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Future milestone payments	75,000,000
Biogen Collaboration Agreement [Member] \| SAGE-217 [Member] \| Maximum [Member] \| Sales Milestones [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Future milestone payments	300,000,000.0
Biogen Collaboration Agreement [Member] \| SAGE-217 [Member] \| Maximum [Member] \| Regulatory and Commercial Milestones [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Future milestone payments	475,000,000.0
Biogen Collaboration Agreement [Member] \| SAGE-324 [Member] \| Maximum [Member] \| Sales Milestones [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Future milestone payments	300,000,000.0
Biogen Collaboration Agreement [Member] \| SAGE-324 [Member] \| Maximum [Member] \| Regulatory and Commercial Milestones [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Future milestone payments	$ 520,000,000.0
Biogen Stock Purchase Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment										875,000,000.0
Purchase price										650,000,000.0
Transaction price, total										1,100,000,000
Premium amount on equity investment										$ 232,500,000
Price per share										$ 104.14
Premium on per share price										40.00%
Biogen stock purchase agreement, description								The standstill restrictions terminate on the earliest of (i) a specified regulatory milestone under the Biogen Collaboration Agreement, (ii) the date one year following the termination of the Biogen Collaboration Agreement and (iii) the seventh anniversary of the Effective Date. BIMA also agreed not to, and to cause its affiliates not to, sell or transfer any of the Biogen Shares for a period of eighteen months from the closing of the sale of the Biogen Shares, which period expired on June 30, 2022, and to limit sales and transfers of the Biogen Shares for an additional eighteen-month period, which expires December 31, 2023, in each case subject to specified conditions and exceptions.
Stock issued										$ 417,500,000