104 The cover page from this Current Report on Form 8-K formatted in Inline XBRL (included as Exhibit 101) 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. Compass Therapeutics, Inc. Date: August 6, 2026 By: /s/ Neil Lerner Neil Lerner Chief Accounting Officer

104 The cover page from this Current Report on Form 8-K formatted in Inline XBRL (included as Exhibit 101) 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. Compass Therapeutics, Inc. Date: May 5, 2026 By: /s/ Neil Lerner Neil Lerner Chief Accounting Officer

104 The cover page from this Current Report on Form 8-K formatted in Inline XBRL (included as Exhibit 101) 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. Compass Therapeutics, Inc. Date: March 5, 2026 By: /s/ Neil Lerner Neil Lerner Chief Accounting Officer

Results of Operations and Financial Condition. The information contained in

104 The cover page from this Current Report on Form 8-K formatted in Inline XBRL (included as Exhibit 101) 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. Compass Therapeutics, Inc. Date: November 5, 2025 By: /s/ Neil Lerner Neil Lerner Chief Accounting Officer

Entry into a Material Definitive Agreement On August 12, 2025, Compass Therapeutics, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Jefferies LLC, Piper Sandler & Co., and Guggenheim Securities, LLC, as representatives (the “Representatives”) of the underwriters named therein (the “Underwriters”), pursuant to which the Company agreed to issue and sell an aggregate of (a) 33,290,000 shares (the “Firm Shares”) of its common stock, par value $0.00…

99.2 Corporate presentation - Earnings Call August 11, 2025 99.3 Corporate presentation of Compass Therapeutics, Inc. dated August 2025 104 Cover Page Interactive Data File (embedded within the Inline XBRL document) 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. Compass Therapeutics, Inc. Date: August 11, 2025 By: /s/ Neil Lerner Neil Lerner Chief…

104 The cover page from this Current Report on Form 8-K formatted in Inline XBRL (included as Exhibit 101) 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. Compass Therapeutics, Inc. Date: May 8, 2025 By: /s/ Neil Lerner Neil Lerner Chief Accounting Officer

104 The cover page from this Current Report on Form 8-K formatted in Inline XBRL (included as Exhibit 101) 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. Compass Therapeutics, Inc. Date: February 27, 2025 By: /s/ Neil Lerner Neil Lerner Chief Accounting Officer

Results of Operations and Financial Condition. The information contained in

Chief Financial Officer — Barry Shin: The company appointed Barry Shin as the new Chief Financial Officer.

104 The cover page from this Current Report on Form 8-K formatted in Inline XBRL (included as Exhibit 101) 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. Compass Therapeutics, Inc. Date: November 12, 2024 By: /s/ Neil Lerner Neil Lerner VP Finance

104 The cover page from this Current Report on Form 8-K formatted in Inline XBRL (included as Exhibit 101) 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. Compass Therapeutics, Inc. Date: August 12, 2024 By: /s/ Neil Lerner Neil Lerner VP Finance

CEO — Vered Bisker-Leib: Dr. Vered Bisker-Leib resigned as CEO and from the Board of Directors, with a consulting agreement in place.

104 Cover Page Interactive Data File (embedded within the Inline XBRL document) 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. Compass Therapeutics, Inc. Date: May 13, 2024 By: /s/ Neil Lerner Neil Lerner VP Finance

104 Cover Page Interactive Data File (embedded within the Inline XBRL document) 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. Compass Therapeutics, Inc. Date: March 21, 2024 By: /s/ Neil Lerner Neil Lerner VP Finance

Chief Executive Officer — Vered Bisker-Leib, PhD: Dr. Vered Bisker-Leib was promoted to Chief Executive Officer and received a significant equity award.

shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing. Forward-Looking Statements The Company cautions readers that statements contained in this report regarding matte…

104 The cover page from this Current Report on Form 8-K formatted in Inline XBRL (included as Exhibit 101) 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. Compass Therapeutics, Inc. Date: November 9, 2023 By: /s/ Neil Lerner Neil Lerner VP Finance

104 The cover page from this Current Report on Form 8-K formatted in Inline XBRL (included as Exhibit 101) 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. Compass Therapeutics, Inc. Date: August 3, 2023 By: /s/ Neil Lerner Neil Lerner VP Finance

104 The cover page from this Current Report on Form 8-K formatted in Inline XBRL (included as Exhibit 101) 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. Compass Therapeutics, Inc. Date: May 4, 2023 By: /s/ Neil Lerner Neil Lerner VP Finance

Class III director and chairman of the Audit Committee — Richard S. Lindahl: Appointment of a new independent director and audit committee financial expert to the Board.

Director — David Wurzer: Resigned for personal family reasons.

Director — David Wurzer: Appointment of a new director to the Board and as chairman of the Audit Committee.

Chief Scientific Officer — Susan Kalled, PhD: Dr. Susan Kalled departed her position as Chief Scientific Officer.