Company: SUPN
Filing Date: 2025-10-16
Form Type: 8-K/A
Source: 0001356576-25-000062
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Company: SUPERNUS PHARMACEUTICALS, INC.
Filing Date: 2025-10-16
Form: 8-K/A
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The Unaudited Interim Financial Statements of Sage Therapeutics, Inc. as of and for the three and six months ended June 30, 2024 and 2025 are filed as Exhibit 99.3 to this amendment, and incorporated herein by reference.

(b) Pro Forma Condensed Combined Financial Information

The Unaudited Pro Forma Condensed Combined Balance Sheet as of June 30, 2025, Unaudited Pro Forma Condensed Combined Statement of Operations for the six months ended June 30, 2025 and Unaudited Pro

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Forma Condensed Combined Statement of Operations for the year ended December 31, 2024 filed as Exhibit 99.4 to this amendment and incorporated herein by reference.

(c) Exhibits

Exhibit 23.1 - Consent of PricewaterhouseCoopers LLP dated October 16, 2025.

Exhibit 99.2 - Audited Annual Financial Statements of Sage Therapeutics, Inc. as of and for the fiscal years ended 2023and 2024 (incorporated by reference from Item 9A, and pages 120 and F-1 through F-40 of the Sage Therapeutics Annual Report on Form 10-K filed by Sage Therapeutics, Inc. on February 11, 2025).

Exhibit 99.3 - Unaudited Interim Financial Statements of Sage Therapeutics, Inc. as of and for the three and six months ended June 30, 2024and 2025 (incorporated by reference from pages 7 through 37 of the Sage Therapeutics Quarterly Report on Form 10-Q filed by Sage Therapeutics, Inc. on July 30, 2025).

Exhibit 99.4 — Unaudited Pro Forma Condensed Combined Balance Sheet as of June 30, 2025, Unaudited Pro Forma Condensed Combined Statement of Operations for the six months ended June 30, 2025 and Unaudited Pro Forma Condensed Combined Statement of Operations for the year ended December 31, 2024.

Exhibit 104 — The cover page from this Current Report on Form 8-K, formatted in Inline XBRL.

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### SIGNATURES
Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned