Amendment: Day One Biopharmaceuticals Inc. filed SEC Form 8-K: Financial Statements and Exhibits

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
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FORM 8-K/A

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(AMENDMENT NO. 1)
CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): January 06, 2026

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DAY ONE BIOPHARMACEUTICALS, INC.
(Exact name of Registrant as Specified in Its Charter)
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Registrant’s Telephone Number, Including Area Code: (650) 484-0899

N/A

(Former Name or Former Address, if Changed Since Last Report)

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Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Explanatory Note

This Amendment No. 1 on Form 8-K/A (this “Amendment No. 1”) amends the Current Report on Form 8-K filed by Day One Biopharmaceuticals, Inc. (“Parent”) on January 6, 2026 (the “Original Report”), in which Parent reported, among other events, the completion of the Merger (as defined in the Original Report). This Amendment No. 1 is filed to (i) update the information in Item 9.01(a) of the Original Report to include the audited consolidated financial statements of Target (as defined in the Original Report) as of and for the years ended December 31, 2024 and December 31, 2023 and to include the unaudited interim condensed consolidated financial statements of Target as of and for the three and nine months ended September 30, 2025; and (ii) update the information in Item 9.01(b) of the Original Report to include the unaudited pro forma condensed combined financial information of Parent and Target (collectively, the "Company") as of and for the nine months ended September 30, 2025 and the year ended December 31, 2024. This Amendment No. 1 does not amend any other item of the Original Report or purport to provide an update or a discussion of any developments at the Company subsequent to the filing date of the Original Report.

Item 9.01 Financial Statements and Exhibits.

(a) Financial Statements of Business Acquired

The audited consolidated financial statements of Target as of and for the years ended December 31, 2024 and December 31, 2023 and the related notes thereto have been audited by Ernst & Young LLP, Target’s independent auditor, as set forth in its reports thereon, are incorporated herein by reference as Exhibit 99.1 and Exhibit 99.2, respectively.

The unaudited interim condensed consolidated financial statements of Target as of and for the three and nine months ended September 30, 2025 and the related notes thereto are incorporated herein by reference as Exhibit 99.3.

(b) Pro Forma Financial Information

The unaudited pro forma condensed combined financial information of the Company as of and for the nine months ended September 30, 2025 and the year ended December 31, 2024 is attached hereto as Exhibit 99.4 and incorporated herein by reference.

(d) Exhibits.

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# Certain annexes, exhibits and schedules have been omitted pursuant to Item 601(a)(5) of Regulation S-K. The registrant hereby undertakes to furnish supplemental copies of any of the omitted annexes and schedules upon request by the SEC.

SIGNATURE

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 hereunto duly authorized.