This Amendment No. 1 (this “Amendment”) to Schedule
14D-9 amends and supplements the Solicitation/Recommendation Statement on Schedule 14D-9 previously filed by Decibel Therapeutics, Inc., a Delaware corporation
(“Decibel”), with the U.S. Securities and Exchange Commission (the “SEC”) on August 25, 2023 (as it may be further amended or supplemented from time to time, the “Schedule
14D-9”), with respect to the tender offer by Symphony Acquisition Sub, Inc., a Delaware corporation (“Purchaser”), and a wholly owned subsidiary of Regeneron Pharmaceuticals, Inc., a New York
corporation (“Regeneron”), to acquire all of the issued and outstanding shares of common stock, of Decibel in exchange for (i) $4.00 per share, payable in cash, without interest and subject to reduction for any applicable withholding of
taxes, plus (ii) one contractual, non-tradeable contingent value right per share (each, a “CVR”), which entitles the holder to potentially receive contingent payments of up to an aggregate of
$3.50 per CVR, without interest and subject to reduction for any applicable withholding taxes, upon the achievement of certain clinical development and regulatory milestones for Decibel’s lead investigational product candidate, DB-OTO, within specified time periods and in accordance with the terms and subject to the conditions of a contingent value rights agreement to be entered into with a rights agent mutually agreeable to Regeneron and
Decibel, upon the terms and subject to the conditions set forth in the Offer to Purchase, dated as of August 25, 2023 (together with any amendments or supplements thereto, the “Offer to Purchase”), and in the related Letter of
Transmittal (together with any amendments or supplements thereto, the “Letter of Transmittal,” which, together with the Offer to Purchase, constitute the “Offer”). The Offer is described in a Tender Offer Statement on Schedule TO
(as amended or supplemented from time to time, the “Schedule TO”) filed jointly by Regeneron and Purchaser with the SEC on August 25, 2023. The Offer to Purchase and the Letter of Transmittal have been filed as Exhibits (a)(1)(A) and
(a)(1)(B) to the Schedule 14D-9, respectively.
Capitalized terms used in this Amendment but not defined herein
shall have the respective meanings given to such terms in the Schedule 14D-9. The information set forth in the Schedule 14D-9 remains unchanged and is incorporated
herein by reference, except that such information is hereby amended or supplemented to the extent specifically provided herein.
Item 8.
Additional Information.
Item 8 of the Schedule 14D-9 is hereby amended and supplemented by replacing in its
entirety the paragraph under “—(e) Legal Proceedings” on page 54 of the Schedule 14D-9 with the following:
“On August 28, 2023, Shoshana Minzer, a purported stockholder of Decibel, filed a complaint in the United States District Court for the Southern
District of New York, captioned Minzer v. Decibel Therapeutics, Inc., et al., 1:23-cv-07626 (S.D.N.Y.) (the “Minzer Complaint”). On August 29,
2023, Catherine Coffman, a purported stockholder of Decibel, filed a complaint in the United States District Court for the Southern District of New York, captioned Coffman v. Decibel Therapeutics, Inc., et al.,
1:23-cv-07668 (S.D.N.Y.) (the “Coffman Complaint”). Also on August 29, 2023, Ryan O’Dell, a purported stockholder of Decibel, filed a complaint in
the United States District Court for the Southern District of New York, captioned O’Dell v. Decibel Therapeutics, Inc., et al., 1:23-cv-07672 (S.D.N.Y.) (the
“O’Dell Complaint”). On August 30, 2023, John Clark, a purported stockholder of Decibel, filed a complaint in the United States District Court for the District of Delaware, captioned Clark v. Decibel Therapeutics, Inc., et
al., 1:23-cv-00946 (D. Del.) (the “Clark Complaint”). On September 1, 2023, Elaine Wang, a purported stockholder of Decibel, filed a complaint in the
United States District Court for the Southern District of New York, captioned Wang v. Decibel Therapeutics, Inc., et al., 1:23-cv-07816 (S.D.N.Y.) (the “Wang
Complaint”). On September 6, 2023, Lisa Vorel, a purported stockholder of Decibel, filed a complaint in the United States District Court for the Southern District of New York, captioned Vorel v. Decibel Therapeutics, Inc., et al., 1:23-cv-07899 (S.D.N.Y.) (the “Vorel Complaint” and, collectively with the Minzer Complaint, the Coffman Complaint, the O’Dell Complaint, the Clark Complaint,
and the Wang Complaint, the “Complaints”).
The Complaints name as defendants Decibel and each member of the Decibel Board. The Complaints
allege, among other things, that the defendants violated Sections 14(d), 14(e), and 20(a) of the Exchange Act and Rule 14d-9 promulgated thereunder by omitting and/or misrepresenting certain material facts
related to the transaction from the Schedule 14D-9 filed by Decibel on August 25, 2023. The Complaints seek, among other relief, (i) injunctive relief preventing the consummation of the Merger,
(ii) rescission of the Merger Agreement or rescissory damages, (iii) other damages purportedly incurred on account of the alleged omissions or misstatements, and (iv) an award of plaintiffs’ costs and disbursements of the action,
including attorneys’ and expert fees and expenses. Decibel believes that the Complaints are without merit.
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