UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q/A

(Amendment No. 1)

(Mark One)

For the quarterly period ended June 30, 2017

or

Commission File Number: 001-32587

ALTIMMUNE, INC.

(Exact name of registrant as specified in its charter)

(240) 654-1450

(Registrant’s telephone number, including area code)

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    Yes  ☒    No  ☐

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data file required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    Yes  ☒    No  ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer”, “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

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.  ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act).    Yes  ☐    No  ☒

Indicate the number of shares outstanding of each of the issuer’s classes of common stock, as of the latest practicable date: The number of shares of the registrant’s Common Stock, par value $0.0001 per share, outstanding as of August 8, 2017 was 15,422,913

EXPLANATORY NOTE

Altimmune, Inc. (the “Company”) is filing this Amendment No. 1 to its Quarterly Report on Form 10-Q (this “Amendment”) to amend the Company’s Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2017, as filed with the Securities and Exchange Commission (the “SEC”) on August 14, 2017 (the “10-Q”). This Amendment is being filed solely to re-file a revised redacted version of Exhibit 10.7 to the 10-Q to reflect changes to the Company’s confidential treatment request with respect to certain portions of Exhibit 10.7, and in connection therewith, to amend and restate Part II, Item 6 of the 10-Q. In addition, as required by Rule 12b-15 under the Securities Exchange Act of 1934, as amended, new certifications pursuant to SEC Rule 13a-14(a)/15d-14(a) by the Company’s principal executive officer and principal financial officer are filed as exhibits to this Amendment.

No attempt has been made in this Amendment to modify or update the financial statements or other disclosures presented in the 10-Q. This Amendment does not reflect events occurring after the filing of the 10-Q or modify or update those disclosures that may be affected by subsequent events. Accordingly, this Amendment should be read in conjunction with the 10-Q and the Company’s other filings with the SEC.

Item 6. Exhibits

Exhibit Index

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused the report to be signed on its behalf by the undersigned, thereunto duly authorized.