CMPX

Form 8-KFalse000173802100017380212026-03-052026-03-05iso4217:USDxbrli:sharesiso4217:USDxbrli:shares

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported):  March 5, 2026

Compass Therapeutics, Inc. (Exact name of registrant as specified in its charter)

Delaware001-3969682-4876496 (State or Other Jurisdiction of Incorporation)(Commission File Number)(I.R.S. Employer Identification No.) 80 Guest Street, Suite 601 Boston, Massachusetts 02135 (Address of Principal Executive Offices) (Zip Code) (617) 500-8099 (Registrant's telephone number, including area code) Not Applicable (Former name or former address, if changed since last report)

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: ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Securities registered pursuant to Section 12(b) of the Act: Title of each classTrading Symbol(s)Name of each exchange on which registered Common Stock, $0.0001 par value per shareCMPXNASDAQ Capital Market

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. ☐

Item 2.02. Results of Operations and Financial Condition.

On March 5, 2026, Compass Therapeutics, Inc. issued a press release announcing financial results for the year ended December 31, 2025. A copy of the press release is furnished as Exhibit 99.1 to this report and incorporated herein by reference.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits

Exhibit No. Exhibit

99.1 Press Release dated March 5, 2026 (furnished pursuant to Item 2.02) 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, 2026By: /s/ Neil Lerner Neil Lerner Chief Accounting Officer

Form 8-KFalse000173802100017380212026-01-062026-01-06iso4217:USDxbrli:sharesiso4217:USDxbrli:shares

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

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 6, 2026

Compass Therapeutics, Inc. (Exact name of registrant as specified in its charter)

Delaware001-3969682-4876496 (State or Other Jurisdiction of Incorporation)(Commission File Number)(I.R.S. Employer Identification No.) 80 Guest Street, Suite 601 Boston, Massachusetts 02135 (Address of Principal Executive Offices) (Zip Code) (617) 500-8099 (Registrant's telephone number, including area code) Not Applicable (Former name or former address, if changed since last report)

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: ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Securities registered pursuant to Section 12(b) of the Act: Title of each classTrading Symbol(s)Name of each exchange on which registered Common Stock, $0.0001 par value per shareCMPXNASDAQ Capital Market

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. ☐

Item 2.02. Results of Operations and Financial Condition.

The information contained in Item 8.01 of this Current Report, to the extent required, is incorporated into this Item 2.02 by reference.

Item 8.01. Other Events.

On January 6, 2026, Compass Therapeutics, Inc. (the “Company”) issued a press release titled “Compass Therapeutics Provides Corporate Update". A copy of the press release is attached hereto as Exhibit 99.1 and is incorporated herein by reference.

The Company disclosed its estimate that cash, cash equivalents and marketable securities were approximately $209 million as of December 31, 2025. This amount is unaudited and preliminary and is subject to the completion of financial closing procedures. As a result, this amount may differ materially from the amount that will be reflected in the Company’s financial statements as of and for the year ended December 31, 2025.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits

Exhibit No. Exhibit

99.1 Press Release dated January 6, 2026 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: January 6, 2026By: /s/ Neil Lerner Neil Lerner Chief Accounting Officer

Form 8-KFalse000173802100017380212025-11-052025-11-05iso4217:USDxbrli:sharesiso4217:USDxbrli:shares

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported):  November 5, 2025

Compass Therapeutics, Inc. (Exact name of registrant as specified in its charter)

Delaware001-3969682-4876496 (State or Other Jurisdiction of Incorporation)(Commission File Number)(I.R.S. Employer Identification No.) 80 Guest Street, Suite 601 Boston, Massachusetts 02135 (Address of Principal Executive Offices) (Zip Code) (617) 500-8099 (Registrant's telephone number, including area code) Not Applicable (Former name or former address, if changed since last report)

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: ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Securities registered pursuant to Section 12(b) of the Act: Title of each classTrading Symbol(s)Name of each exchange on which registered Common Stock, $0.0001 par value per shareCMPXNASDAQ Capital Market

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. ☐

Item 2.02. Results of Operations and Financial Condition.

On November 5, 2025, Compass Therapeutics, Inc. issued a press release announcing financial results for the quarter and nine months ended September 30, 2025. A copy of the press release is furnished as Exhibit 99.1 to this report and incorporated herein by reference.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits

Exhibit No. Exhibit

99.1 Press Release dated November 5, 2025 (furnished pursuant to Item 2.02) 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, 2025By: /s/ Neil Lerner Neil Lerner Chief Accounting Officer