Exhibit 5.1
February 14, 2024
+1 617 526 6000 (t)
+1 617 526 5000
(f)
@wilmerhale.com
Sage Therapeutics, Inc
215 First Street
Cambridge, MA 02142
Re: 2014 Stock Option and Incentive Plan
Ladies and Gentlemen:
We have assisted in the preparation of a Registration Statement on Form S-8 (the
Registration Statement) to be filed with the Securities and Exchange Commission (the Commission) under the Securities Act of 1933, as amended (the Securities Act), relating to an aggregate of 2,401,745 shares of
common stock, $0.0001 par value per share (the Shares), of Sage Therapeutics, Inc., a Delaware corporation (the Company), issuable under the Companys 2014 Stock Option and Incentive Plan (the Plan).
We have examined the Certificate of Incorporation and Bylaws of the Company, each as amended and restated to date, and originals, or copies
certified to our satisfaction, of all pertinent records of the meetings of the board of directors and stockholders of the Company, the Registration Statement, the Plan and such other documents relating to the Company as we have deemed material for
the purposes of this opinion.
In our examination of the foregoing documents, we have assumed the genuineness of all signatures, the
authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as certified, photostatic or other copies, the authenticity of the originals of any such documents and the legal
competence of all signatories to such documents.
We assume that the appropriate action will be taken, prior to the offer and sale of the
Shares in accordance with the Plan, to register and qualify the Shares for sale under all applicable state securities or blue sky laws.
We express no opinion herein as to the laws of any state or jurisdiction other than the General Corporation Law of the State of Delaware.
It is understood that this opinion is to be used only in connection with the offer and sale of the Shares while the Registration Statement is
in effect.