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): June 15, 2020

CELLDEX THERAPEUTICS, INC.

(Exact name of registrant as specified in its charter)

Perryville III Building, 53 Frontage Road, Suite 220,
Hampton, New Jersey 08827

(Address of principal executive offices) (Zip Code)

(908) 200-7500

(Registrant’s telephone number, including area code)

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. ¨

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

Item 1.01 Entry into a Material Definitive Agreement.

On June 15, 2020, Celldex Therapeutics, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Cantor Fitzgerald & Co. (the “Representative”), as representative of several underwriters named therein (the “Underwriters”), relating to the offering, issuance and sale of 13,377,926 shares (the “Shares”) of the Company’s common stock, par value $0.001 (the “Common Stock”), at a price to the public of $9.75 per share (the “Offering”). The net proceeds to the Company from the Offering are expected to be approximately $122.7 million, after deducting underwriting discounts and commissions and other estimated offering expenses payable by the Company. The Offering is expected to close on or about June 18, 2020, subject to customary closing conditions. Pursuant to the Underwriting Agreement, the Underwriters have a 30-day option to purchase up to 2,006,688 additional shares of Common Stock on the same terms as the Underwriters are purchasing the Shares.

The Offering is being made pursuant to the Company’s effective registration statement on Form S-3 (File No. 333-235399 and 333-239199) previously filed with and declared effective by the Securities and Exchange Commission (the “SEC”) and a prospectus supplement and accompanying prospectus filed with the SEC.

The Underwriting Agreement contains customary representations, warranties and agreements by the Company, conditions to closing, indemnification obligations of the Company and the Underwriters, including for liabilities under the Securities Act of 1933, as amended, other obligations of the parties and termination provisions. The representations, warranties and covenants contained in the Underwriting Agreement were made only for purposes of such agreement and as of specific dates, were solely for the benefit of the parties to such agreement, and may be subject to limitations agreed upon by the contracting parties.

The foregoing description of the Underwriting Agreement is not complete and is qualified in its entirety by reference to the full text of the Underwriting Agreement, a copy of which is filed as Exhibit 1.1 to this Current Report and is incorporated by reference herein. A copy of the opinion of Lowenstein Sandler LLP relating to the legality of the issuance and sale of Shares in the Offering is attached as Exhibit 5.1 to this Current Report.

Item 8.01 Other Events.

On June 15, 2020, the Company issued a press release regarding the launch of the Offering. On June 15, 2020, the Company also issued a press release announcing that it had priced the Offering. Copies of the launch press release and pricing press release are furnished hereto as Exhibits 99.1 and 99.2, respectively, to this Current Report and incorporated herein by reference.

Statements contained in this Current Report on Form 8-K regarding matters that are not historical facts are “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. Such statements may involve risks and uncertainties, such as statements related to the anticipated closing of the Offering and the amount of proceeds expected from the Offering. The risks and uncertainties involved include the Company’s ability to satisfy certain conditions to closing on a timely basis or at all, as well as other risks detailed from time to time in the Company’s SEC filings, including in its annual filing on Form 10-K filed with the SEC on March 26, 2020, the preliminary prospectus supplement filed with the SEC on June 15, 2020, and the final prospectus supplement to be filed with the SEC.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits.

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.