Sage Therapeutics to Provide Pipeline Update at J.P. Morgan Healthcare Conference and Outline Key 2018 Initiatives to Support Planned Evolution to a Fully-Integrated Commercial Biopharmaceutical Company Company evolving,

Sage Therapeutics to Provide Pipeline Update at J.P. Morgan Healthcare Conference and Outline Key 2018

Initiatives to Support Planned Evolution to a Fully-Integrated Commercial Biopharmaceutical Company

Company evolving, as

planned, to be a leading, innovative CNS company

2018 strategy focuses on continued R&D innovation, pipeline

expansion and commercialization plans for new classes of CNS therapeutics

CAMBRIDGE, Mass. January 8, 2018

Sage Therapeutics (NASDAQ: SAGE), a clinical-stage biopharmaceutical company developing novel medicines to treat life-altering central nervous system (CNS) disorders, today announced that in a corporate presentation at the 36th Annual J.P. Morgan Healthcare Conference in San Francisco, the Company s Chief Executive Officer, Jeff Jonas, M.D., will discuss several components of the Company s strategy to build the

business for the long term by assembling the capabilities to fully develop and commercialize important medicines. His remarks will highlight three key areas of focus in the pursuit of new classes of CNS therapies: impacting novel, fundamental brain

mechanisms; addressing treatment gaps with differentiated therapies; and discovering a potentially groundbreaking approach to depressive disorders.

The lack of adequate treatments for CNS disorders is creating a global public health crisis due to limited innovation in neuroscience research and

development until now, said Dr. Jonas. Sage is taking on this challenge with a deliberate, planned approach. By thinking differently about CNS drug development, we are originating differentiated medicines with the

potential to exceed expectations, customizing the playbook of commercialization, and disrupting conventional wisdom by creating a potential new methodology of care. In 2018, we expect to build on our track record of success, with the potential to

create significant value by maximizing patient benefit.

Dr. Jonas will provide additional detail on the following development programs:

Sage is currently focused on launch

readiness and building commercial infrastructure to ensure successful commercial execution, if Sage s proprietary formulation brexanolone is approved to address postpartum depression (PPD), a common biological complication of childbirth.

Sage s novel, oral, next-generation positive allosteric modulators of synaptic and extra-synaptic GABAA receptors.

GABA Discovery Programs

first-in-class oxysterol-based positive allosteric modulators of the NMDA receptor.

The Company recently selected SAGE-904 as its second NMDA receptor

positive allosteric modulator product candidate for development. Positive modulation of NMDA receptors may have potential in the treatment of a range of neurological disorders associated with a variety of cognitive, neurological and behavioral

2017 Year-End Cash Guidance

Sage ended 2017 with approximately $518 million of cash, cash equivalents and marketable securities, including $325.7 million in net proceeds from a public

offering completed in November 2017. Based on its current operating plans, Sage expects that its operating expenses will increase year over year in 2018 to support continued pipeline advancement and potential product commercialization of brexanolone

in PPD. Sage expects to provide specific 2018 financial guidance in its fourth quarter and full year 2017 financial results announcement in February 2018.

Webcast Information for JP Morgan Presentation

scheduled to present on Tuesday, January 9, 2018 at 11:30 a.m. Pacific Time (2:30 p.m. Eastern Time), followed by a Q&A session. A live webcast of the presentation and Q&A session can be accessed on the investor page of Sage s

website at investor.sagerx.com. A replay of the webcast will be available on Sage s website approximately two hours after the completion of the event and will be archived for up to 30 days.

About Sage Therapeutics

Sage Therapeutics is a

clinical-stage biopharmaceutical company committed to developing novel medicines to transform the lives of patients with life-altering central nervous system (CNS) disorders. Sage has a portfolio of novel product candidates targeting critical CNS

receptor systems, GABA and NMDA. Sage s lead program, a proprietary IV formulation of brexanolone (SAGE-547), has completed two Phase 3 clinical trials in postpartum depression. Sage is developing its next generation modulators, including

SAGE-217 and SAGE-718, in various CNS disorders. For more information, please visit www.sagerx.com.

Forward-Looking Statements

Various statements in this release concern Sage s future expectations, plans and prospects, including without limitation: our expectations regarding

the timing of a potential NDA filing and launch of our proprietary formulation of brexanolone in PPD, and the expected build of commercial infrastructure and supply chain; our statements regarding plans for further development of our product

candidates and related activities and our view of the potential for successful development; our views as to the opportunity represented by Sage s portfolio and business, and the potential for value creation; and our expectations with respect to

future use of cash. These forward-looking statements are neither promises nor guarantees of future performance, and are subject to a variety of risks and uncertainties, many of which are beyond our control, which could cause actual results to differ

materially from those contemplated in these forward-looking statements, including the risks that: the clinical and non-clinical data we have generated with our proprietary formulation of brexanolone to date may be determined by regulatory

authorities, despite prior advice, to be insufficient to file for or gain regulatory approval to launch and commercialize our product in PPD and regulatory authorities may determine that additional trials or data are necessary in order to file for

or obtain approval; regulatory authorities may find fault with the data generated at particular clinical site or sites or with the activities of our trial monitor or may disagree with our analyses of the results of our trials or identify issues with

our manufacturing or quality systems, and any such findings or issues could require additional data or analyses or changes to our systems that could delay or prevent us from gaining approval of brexanolone; we may encounter

unexpected safety or tolerability issues with brexanolone, SAGE-217 or any of our other product candidates in ongoing or future development; we may not be able to successfully demonstrate the

efficacy and safety of SAGE-217 or any of our other product candidates at each stage of development; success in early stage clinical trials may not be repeated or observed in ongoing or future studies of SAGE-217 or any of our other product

candidates; ongoing and future clinical results may not support further development or be sufficient to gain regulatory approval to market SAGE-217 or any of our other product candidates; we may decide that a development pathway for one of our

product candidates in one or more indications is no longer feasible or advisable or that the unmet need no longer exists; decisions or actions of the FDA or other regulatory agencies may affect the initiation, timing, design, size, progress and cost

of clinical trials and our ability to proceed with further development; we may experience slower than expected enrollment in ongoing clinical trials; the internal and external costs required for our activities, and to build our organization in

connection with such activities, and the resulting use of cash, may be higher than expected, or we may conduct additional clinical trials or pre-clinical studies, or engage in new activities, requiring additional expenditures and using cash more

quickly than anticipated; and we may encounter technical and other unexpected hurdles in the development and manufacture of our product candidates; as well as those risks more fully discussed in the section entitled Risk Factors in our

most recent Quarterly Report on Form 10-Q, and discussions of potential risks, uncertainties, and other important factors in our subsequent filings with the Securities and Exchange Commission. In addition, any forward-looking statements represent

our views only as of today, and should not be relied upon as representing our views as of any subsequent date. We explicitly disclaim any obligation to update any forward-looking statements.