Sage Therapeutics Announces Fourth Quarter and Full Year 2018 Financial Results and Highlights Pipeline and Business Progress Planned U.S. commercial launch of ZULRESSO (brexanolone) injection, if approved, on track for

Sage Therapeutics Announces Fourth Quarter and Full Year 2018 Financial Results and Highlights Pipeline

and Business Progress

Planned U.S. commercial launch of ZULRESSO

(brexanolone) injection, if approved, on track for June 2019, based on PDUFA target date of March 19, 2019 and anticipated DEA scheduling

Topline data from Phase 3 trial of SAGE-217 in MDD expected in Q4 2019 or 1Q 2020

Neurology and neuropsychiatry franchises continue to progress with positive Phase 1 data

Conference call today at 8:00 AM ET

CAMBRIDGE, Mass., February 19, 2019 Sage Therapeutics, Inc. (NASDAQ: SAGE), a clinical-stage biopharmaceutical company

developing novel medicines to treat life-altering central nervous system (CNS) disorders, today reported business highlights and financial results for the fourth quarter and full year ended December 31, 2018.

Eight years ago, Sage was founded to address the innovation void in CNS drug development. Today we are establishing Sage as a CNS leader by building

multiple franchise opportunities in depression, neurology and neuropsychiatry, with the potential to treat millions of patients. Our focused execution across these three franchises has led to a pipeline of four clinical candidates across

several indications, all using novel mechanisms and approaches, said Jeff Jonas, M.D., chief executive officer at Sage. The expected near-term approval of our lead product candidate, ZULRESSO in the treatment of postpartum depression,

will mark a major milestone in our company s journey and, along with our broader portfolio, may help support a paradigm-shifting approach to mental health. We want people to be treated as people with depression, not depressed people, and we

believe our development programs, if successful, can help define this new normal.

Depression Franchise:

Led by ZULRESSO (brexanolone) injection, which has been designated as a breakthrough therapy by

the U.S. Food and Drug Administration (FDA) for the treatment of postpartum depression (PPD), and SAGE-217, which has been designated as a breakthrough therapy for the treatment of major depressive disorder

Neurology Franchise:

Led by SAGE-324, a next-generation positive allosteric modulator (PAM) of GABAA receptors in development as a potential therapy for neurological conditions, such as

essential tremor and epileptiform disorders.

Neuropsychiatry Franchise:

Led by first-in-class NMDA receptor PAM, SAGE-718, which is in development as a potential therapy for certain cognition-related disorders

impacted by NMDA receptor dysfunction

Financial Results for the Fourth Quarter and Full Year 2018

Conference Call Information

Sage will host a conference call and webcast today at 8:00 AM ET to discuss its fourth quarter and full year 2018 financial results and recent

corporate updates. The live webcast can be accessed on the investor page of Sage s website at investor.sagerx.com. The conference call can be accessed by dialing 1-866-450-8683 (toll-free domestic) or 1-281-542-4847 (international) and using

the conference ID 6968949. 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

CNS disorders. Sage s lead product candidate, ZULRESSO (brexanolone) injection, has completed Phase 3 clinical development for postpartum depression and a New Drug Application is currently under review with the U.S. Food and Drug

Administration. Sage is developing a portfolio of novel product candidates targeting critical CNS receptor systems, including SAGE-217, which is in Phase 3 development in major depressive disorder and

postpartum depression. 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

approval of our new drug application (NDA) for ZULRESSO in the treatment of PPD, including the target timing of a decision by the FDA; our plans regarding the timing of launch of ZULRESSO in PPD, future commercial activities, and the potential for

future revenues, if the NDA for ZULRESSO is approved; our statements regarding plans and timelines for development of SAGE-217 and our other product candidates, including planned clinical and regulatory

activities; our view of the potential for the data from our development program with SAGE-217 in MDD, if positive, to create value and be supportive of a regulatory submission and approval; our views as to the

opportunity represented by Sage s portfolio and business in CNS, including the potential, if we are successful, to treat millions of patients and to change treatment paradigms; and our expectations regarding increases in operating expense, use

of cash and future cash needs. 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 FDA may decide not to approve our NDA for ZULRESSO in PPD; the clinical and non-clinical

data we have generated with ZULRESSO to date may be determined by the FDA to be insufficient to gain regulatory approval to launch and commercialize our product in PPD and FDA may determine that additional trials or data are necessary in order to

file for or obtain approval; the FDA may not complete its review of our filing within the target timelines; even if ZULRESSO is successfully approved for PPD in the U.S., we may encounter issues, delays or other challenges in launching or

commercializing the product, including issues related to market acceptance and reimbursement, challenges associated with restrictions or conditions that may be imposed by regulatory authorities, including challenges related to limiting the site of

administration to a certified healthcare facility monitored by a qualified healthcare provider, and the necessity for a REMS; and challenges associated with execution of our sales and patient support activities, which in each case could limit the

potential of our product; we may encounter unexpected safety or tolerability issues with ZULRESSO, SAGE-217 or any of our other product candidates in ongoing or future development; we may not be successful in

our development of SAGE-217 or any of our other product candidates in any indication we are currently pursuing or may in the future pursue; 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 of

our 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; the FDA may decide that our development program

for SAGE-217, even if positive, is not sufficient for an NDA filing or approval; 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 or may impact the regulatory pathway; 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, manufacture and potential future commercialization of our product candidates; as well as those risks more fully discussed in the section entitled Risk Factors in our most recent

report filed with the Securities and Exchange Commission (SEC), and discussions of potential risks, uncertainties, and other important factors in our subsequent filings with the SEC. 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.

Sage Therapeutics, Inc. and Subsidiaries

Condensed Consolidated Statements of Operations

(in thousands, except share and per share data)

Sage Therapeutics, Inc. and Subsidiaries

Condensed Consolidated Balance Sheets