UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

(Rule 14a-101)

INFORMATION REQUIRED IN PROXY STATEMENT

SCHEDULE 14A INFORMATION

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Securities Exchange Act of 1934

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☐ Definitive Proxy Statement

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Sage Therapeutics, Inc.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than Registrant)

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Your Vote Counts! SAGE THERAPEUTICS, INC. 2022 Annual Meeting Vote by June 15, 2022 11:59 PM ET SAGE THERAPEUTICS, INC. 215 FIRST STREET CAMBRIDGE, MA 02142 D80442-P69408 You invested in SAGE THERAPEUTICS, INC. and it’s time to vote! You have the right to vote on proposals being presented at the Annual Meeting. This is an important notice regarding the availability of proxy material for the stockholder meeting to be held on June 16, 2022. Get informed before you vote View the Notice and Proxy Statement and Annual Report online OR you can receive a free paper or email copy of the material(s) by requesting prior to June 2, 2022. If you would like to request a copy of the material(s) for this and/or future stockholder meetings, you may (1) visit www.ProxyVote.com, (2) call 1-800-579-1639 or (3) send an email to sendmaterial@proxyvote.com. If sending an email, please include your control number (indicated below) in the subject line. Unless requested, you will not otherwise receive a paper or email copy. For complete information and to vote, visit www.ProxyVote.com Control # Vote Virtually at the Meeting* June 16, 2022 9:00 a.m. Eastern Time Smartphone users Point your camera here and vote without entering a control number Virtually at: www.virtualshareholdermeeting.com/SAGE2022 *Please check the meeting materials for any special requirements for meeting attendance. V1.1

Vote at www.ProxyVote.com THIS IS NOT A VOTABLE BALLOT This is an overview of the proposals being presented at the upcoming stockholder meeting. Please follow the instructions on the reverse side to vote these important matters. Board Recommends Voting Items 1. To elect three directors, James M. Frates, George Golumbeski, Ph.D., and Kevin P. Starr, each to serve as a Class II director until the 2025 Annual Meeting of Stockholders and until his successor is duly elected and qualified, subject to his earlier death, resignation, or removal; Nominees: For 01) James M. Frates 02) George Golumbeski, Ph.D. 03) Kevin P. Starr 2. To ratify the appointment of PricewaterhouseCoopers LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2022; For 3. To hold a non-binding advisory vote to approve the compensation paid to our named executive officers; For 4. To hold a non-binding advisory vote to determine the frequency of future stockholder advisory votes on the compensation paid to our named executive officers; Year 1 5. To approve an amendment to our 2014 Employee Stock Purchase Plan, as amended, or the 2014 ESPP, to increase the number of shares of our common stock authorized for issuance under the 2014 ESPP by 300,000 shares; and For 6. To transact such other business as may properly come before the meeting or at any and all adjournments or postponements thereof. Prefer to receive an email instead? While voting on www.ProxyVote.com, be sure to click “Sign up for E-delivery”. D80443-P69408