Company: SUPN
Filing Date: 2025-06-16
Form Type: SC TO-C
Source: 0001104659-25-059956
Chunk: 1

Company: SUPERNUS PHARMACEUTICALS, INC.
Filing Date: 2025-06-16
Form: SC TO-C
Chunk 1
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13D under Rule 13d-2. |

Check the following box if the filing is a final amendment reporting the results of the tender offer: ¨

If applicable, check the appropriate box(es) below to designate
the appropriate rule provision(s) relied upon:

| ¨ | Rule 13e-4(i) (Cross-Border Issuer Tender Offer) |

| ¨ | Rule 14d-1(d) (Cross-Border Third-Party Tender Offer) |

This Tender Offer Statement on Schedule TO relates
solely to preliminary communications made before the commencement of a planned tender offer by Saphire, Inc. (“”),
a Delaware corporation and wholly-owned subsidiary of Supernus Pharmaceuticals, Inc. (“”), a Delaware corporation,
for any and all of the outstanding shares of common stock, par value $0.0001 per share, of Sage Therapeutics, Inc. (“”),
to be commenced pursuant to the Agreement and Plan of Merger (the “t”), dated as of June 13, 2025, among
Supernus, Purchaser and Sage.

Important Information

The tender offer for the outstanding common stock
of Sage Therapeutics, Inc. (“Sage”) has not been commenced. This filing does not constitute a recommendation, an offer to
purchase or a solicitation of an offer to sell Sage securities. At the time the tender offer is commenced, Supernus Pharmaceuticals,
Inc. (“Supernus”) and Saphire, Inc., a direct wholly owned subsidiary of Supernus (“Purchaser”), will file a Tender
Offer Statement on Schedule TO (including an Offer to Purchase) with the Securities and Exchange Commission (the “SEC”) and
thereafter, Sage will file a Solicitation/Recommendation Statement on Schedule 14D-9 with the SEC, in each case, with respect to the
tender offer. The solicitation and offer by Supernus and Purchaser to purchase shares of Sage common stock will only be made pursuant
to such Offer to Purchase and related materials. Once filed, investors and security holders are urged to read these materials (including
the Offer to Purchase, a related Letter of Transmittal and certain other tender offer documents, as each may be amended or supplemented
from time to time) carefully since they will contain important information that Sage investors and security holders should consider before
making any decision regarding tendering their common stock, including the terms and conditions of the tender offer. The Tender Offer
Statement, Offer to Purchase,