7. 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 and license 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 was originally eligible to receive additional payments of up to $485.0 million if certain regulatory and commercial milestones were achieved by Shionogi. The potential future milestone payments originally included 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 potential future milestone payments for achievement of specified regulatory milestones were reduced to $55.0 million upon failure to receive FDA approval of zuranolone for the treatment of MDD in the U.S. prior to December 31, 2023. 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. 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 is probable that the Company will collect the consideration to which the Company is 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 three months ended March 31, 2025 and 2024 the Company did not recognize any collaboration revenue from the Company’s agreement with Shionogi.

The Company completed the evaluation of the SSP of each of the performance obligations and determined that the SSP 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 and SAGE-324 products. 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 September 2024, Biogen notified the Company of its termination of the Biogen Collaboration Agreement solely with respect to products containing the Company’s SAGE-324 products on a worldwide basis, effective February 17, 2025 (the “SAGE-324 Termination”), in accordance with the required notice period. As a result of the SAGE-324 Termination, as of February 17, 2025 (the “SAGE-324 Termination effective date”), all licenses granted by the Company to Biogen or by Biogen to the Company regarding the SAGE-324 products expired with respect to the SAGE-324 products on a worldwide basis. Biogen granted to the Company an irrevocable, perpetual license for any Biogen background technology, Biogen collaboration technology or joint collaboration technology that existed as of February 17, 2025 with respect to the SAGE-324 products, in each case in accordance with the terms of the Biogen Collaboration Agreement.

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 is a related party of the Company.

The Company was initially eligible to receive additional payments of up to $1.6 billion from Biogen if certain regulatory and commercial milestones were achieved. The potential future milestone payments for SAGE-217 products included 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. In the fourth quarter of 2023, the Company achieved the $75.0 million milestone for the first commercial sale of ZURZUVAE for the treatment of women with PPD in the U.S. Because the Company and Biogen have agreed not to pursue further development of zuranolone for the treatment of MDD in the U.S., the Company will not receive the $150.0 million milestone payment for the first commercial sale of ZURZUVAE for the treatment of MDD in the U.S.

The potential future milestone payments for SAGE-324 products initially included 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. As a result of the SAGE-324 Termination, the Company will not receive any milestone payments for SAGE-324 products under the Biogen Collaboration Agreement.

The Company is also eligible to receive tiered royalties on net sales of SAGE-217 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 additional milestone payments or any royalty payments under the Biogen Collaboration Agreement.

Development and commercialization activities in the U.S. under the Biogen Collaboration Agreement are conducted pursuant to plans agreed to by the Company and Biogen and overseen by a joint steering committee that consists of an equal number of representatives of each party. The Company and Biogen 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 is solely responsible for all development activities and costs related to any development and commercialization of SAGE-217 products and, prior to the SAGE-324 Termination, SAGE-324 products, for the Biogen Territory, and the Company will receive royalties on any sales in the Biogen Territory, as mentioned above. Biogen is the principal and records sales of SAGE-217 products globally.

The Company is obligated to 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 Biogen Collaboration Agreement, and the Biogen Collaboration Agreement further provides that Biogen 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 (such as the SAGE-324 Termination) 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 low to high 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 at contract inception 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 Biogen Collaboration 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 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. At inception, the Company determined that any variable consideration related to clinical development and regulatory or commercial 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 such, the entirety of the $1.1 billion transaction price was 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 and was recognized as license revenue during the year ended December 31, 2020.

In the fourth quarter of 2023, the Company achieved a milestone for the first commercial sale of ZURZUVAE for the treatment of women with PPD in the U.S. and recognized license and milestone revenue – related party of $75.0 million during the fourth quarter of the year ended December 31, 2023. Payment of the $75.0 million milestone was received during January 2024. During the three months ended March 31, 2025 and 2024, no license and milestone revenue – related party was recognized related to the Biogen Collaboration Agreement.

The Company considers the collaborative activities associated with the co-development, co-commercialization, and co-manufacturing of SAGE-217 products and, through the SAGE-324 Termination effective date, 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.

While Biogen is considered the principal in transactions with customers for the sale of ZURZUVAE globally, the Company is also engaged in significant commercialization activities, including maintaining its own U.S. direct sales force. The Company presents its proportionate share of Biogen’s ZURZUVAE sales to customers in the U.S. as collaboration revenue - related party. Payments to or reimbursements from Biogen related to the agreement of the parties to share equally in all revenue and costs are accounted for as an increase to collaboration revenue, an increase to or reduction of cost of revenues, research and development expenses, or selling, general and administrative expenses, in the consolidated statements of operations and comprehensive loss, depending on the nature of the activity.

To record its proportionate share of collaboration revenue from Biogen’s sales of ZURZUVAE to customers in the U.S., the Company utilizes certain information from Biogen, including revenue from the sale of the product and associated reserves on revenue.

As of March 31, 2025, the Company recorded a collaboration receivable - related party of $10.7 million in the condensed consolidated balance sheet, representing net reimbursement for the amounts due for the three months ended March 31, 2025 and other collaboration revenue for the three months ended March 31, 2025 and three months ended December 31, 2024. As of December 31, 2024, the Company recorded a collaboration receivable – related

party of $9.1 million, representing net reimbursement for the amounts due for the three months ended December 31, 2024.

During the three months ended March 31, 2025, no payments were made to Biogen and the Company received $7.8 million from Biogen for the amounts due for the three months ended December 31, 2024. During the three months ended March 31, 2024, no payments were made to Biogen and the Company received $82.6 million from Biogen for the amounts due for the three months ended December 31, 2023.

During the three months ended March 31, 2025, the Company recorded $0.2 million of other collaboration revenue related to providing development and regulatory support to Biogen in the Biogen Territory under the Biogen Collaboration Agreement. During the three months ended March 31, 2024, no other collaboration revenue was recognized related to the Biogen Collaboration Agreement.

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 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 that 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.

The Company determined the fair value of the common shares was $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 was included in the $1.1 billion transaction price of the Biogen Collaboration Agreement determined above.