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): September 24, 2018

ALTIMMUNE, INC.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number including area code: (240) 654-1450

(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:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (17 CFR §230.405) or Rule 12b-2 of the Securities Exchange Act of 1934 (17 CFR §240.12b-2).

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.  ☐

On September 24, 2018, Altimmune, Inc. (the “Company”) entered into a Securities Purchase Agreement (the “Securities Purchase Agreement”) with certain investors pursuant to which the Company agreed to sell 286,633 shares of the Company’s common stock, par value $0.0001 per share (the “Offering”). Each share of common stock was offered and sold at a price of $17.02.

The Offering is expected to close on or about September 26, 2018, subject to the satisfaction of customary closing conditions. The gross proceeds to the Company after deducting placement agent fees are expected to be approximately $4.5 million, prior to deducting other estimated expenses payable by the Company associated with the Offering. The Offering is being made pursuant to the Company’s existing shelf registration statement on Form S-3 (File No. 333-217034), which was filed with the U.S. Securities and Exchange Commission (the “Commission”) on March 30, 2017 and declared effective by the Commission on April 6, 2017.

The representations, warranties and covenants contained in the Purchase Agreement were made solely for the benefit of the parties to the Purchase Agreement. In addition, such representations, warranties and covenants (i) are intended as a way of allocating the risk between the parties to the Purchase Agreement and not as statements of fact, and (ii) may apply standards of materiality in a way that is different from what may be viewed as material by stockholders of, or other investors in, the Company. Accordingly, the Purchase Agreement is filed with this report only to provide investors with information regarding the terms of transaction, and not to provide investors with any other factual information regarding the Company. Stockholders should not rely on the representations, warranties and covenants or any descriptions thereof as characterizations of the actual state of facts or condition of the Company. Moreover, information concerning the subject matter of the representations and warranties may change after the date of the Purchase Agreement, which subsequent information may or may not be fully reflected in public disclosures.

Roth Capital Partners, LLC acted as placement agent in connection with the Offering pursuant to a Placement Agency Agreement, dated September 24, 2018 (the “Placement Agency Agreement”). Under the Placement Agency Agreement, the placement agent agreed to use reasonable “best efforts” to arrange for the sale of the Common Stock and the Company agreed to pay the placement agent a cash fee equal to 7.0% of the gross proceeds of the Offering. The Placement Agency Agreement contains customary representations, warranties and indemnification by the Company and provides for the reimbursement of up to $125,000 in expenses incurred by the placement agent.

The foregoing description of the Placement Agency Agreement and the Securities Purchase Agreement does not purport to be complete and is qualified in its entirety by reference to the agreements, which are filed as Exhibits 1.1 and 10.1, respectively, to this Current Report on Form 8-K and are incorporated by reference herein.

On September 24, 2018, the Company issued a press release regarding the transactions described above under Item 1.01 of this Current Report on Form 8-K. A copy of the press release is attached hereto as Exhibit 99.1 and is incorporated herein by reference.

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.

Dated September 24, 2018