UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 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): April 28, 2020

ARMATA PHARMACEUTICALS, INC.

(Exact name of Registrant as specified in its charter)

(310) 655-2928

(Registrant’s Telephone number)

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 (see General Instruction A.2. below):

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. ¨

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

Included as Exhibit 99.1 to this report is a copy of a corporate presentation that we intend to utilize in connection with the participation by Armata Pharmaceuticals, Inc. (“Armata”) in a panel discussion on non-antibiotic anti-infectives at the Maxim Group M-Vest Infectious Disease Virtual Conference to be held on May 5, 2020. Armata issued a press release regarding such expected participation on April 28, 2020, a copy of which is attached as Exhibit 99.2 hereto. Exhibits 99.1 and 99.2 are incorporated herein by reference.

The information in this Item 7.01 and the attached Exhibits 99.1 and 99.2 is being furnished and shall not be deemed “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section. The information in this Item 7.01 and the attached Exhibits 99.1 and 99.2 shall not be incorporated by reference into any registration statement or other document pursuant to the Securities Act of 1933, as amended.

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 hereunto duly authorized.