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): February 12, 2020

CATALYST BIOSCIENCES, INC.

(Exact name of registrant as specified in its charter)

611 Gateway Blvd, Suite 710, South

San Francisco, CA 94080

(Address of principal executive offices)

(650) 871-0761

(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:

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

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 1.01 Entry into a Material Definitive Agreement

On February 13, 2020, Catalyst Biosciences, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Raymond James & Associates, Inc., as the representative of the several underwriters named in Schedule I thereto (the “Underwriters”), pursuant to which the Company agreed to issue and sell an aggregate of 4,615,385 shares of its common stock (the “Shares”) to the Underwriters (the “Offering”). The Shares will be sold to the Underwriters at the public offering price of $6.50 per share, less underwriting discounts and commissions. Pursuant to the Underwriting Agreement, the Company has granted the Underwriters a 30-day option to purchase up to an additional 692,307 shares of its common stock. The Underwriting Agreement contains customary representations and warranties, conditions to closing, market standoff provisions, termination provisions and indemnification obligations, including for liabilities under the Securities Act of 1933, as amended (the “Securities Act”). The Offering is being made pursuant to the shelf registration statement on Form S-3 (File No. 333-228970) that was filed by the Company with the Securities and Exchange Commission (“SEC”) on December 21, 2018 and declared effective by the SEC on February 14, 2019 and a related prospectus supplement.

The Company estimates that net proceeds from the Offering will be approximately $27.8 million, after deducting underwriting discounts and commissions and estimated Offering expenses, and assuming no exercise of the Underwriters’ option to purchase additional shares of common stock. The Company intends to use the net proceeds from the Offering for general corporate purposes, which may include clinical and manufacturing activities for MarzAA and DalcA, research and development activities, capital expenditures, selling, general and administrative costs, facilities expansion, and to meet working capital needs. The Company expects the Offering to close on February 18, 2020, subject to customary closing conditions.

The foregoing description of the Underwriting Agreement does not purport to be complete and is qualified in its entirety by reference to the full text of the Underwriting Agreement. A copy of the Underwriting Agreement is filed with this Current Report on Form 8-K as Exhibit 1.1 and is incorporated herein by reference.

A copy of the opinion of Orrick, Herrington & Sutcliffe LLP, relating to the validity of the Shares in connection with the Offering, is filed with this Current Report on Form 8-K as Exhibit 5.1.

Item 2.02. Results of Operations and Financial Condition

On February 12, 2020, the Company filed with the SEC a preliminary prospectus supplement (the “Preliminary Prospectus”) pursuant to Rule 424(b) under the Securities Act of 1933 relating to the Offering. In the Preliminary Prospectus, the Company disclosed that it expects to report that the Company had cash, cash equivalents, and short-term investments of approximately $76.9 million as of December 31, 2019. This amount, which does not include the $15 million upfront payment from Biogen International GmbH in January 2020, is based solely upon information available to it as of the date of this Current Report on Form 8-K, is preliminary, has not been audited and is subject to change pending completion of the Company’s audited financial statements for the year ended December 31, 2019. Additional information and disclosures would be required for a more complete understanding of the Company’s financial position and results of operations as of December 31, 2019. The Company expects to complete its audited financial statements for the year ended December 31, 2019 subsequent to the completion of this offering. It is possible that the Company or its independent registered public accounting firm may identify items that require them to make adjustments to the preliminary estimated cash, cash equivalents and short-term investments balance set forth above and those changes could be material.

The information in this Item 2.02 shall not be deemed to be “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that section or Sections 11 and 12(a)(2) of the Securities Act of 1933. The information contained in this Item 2.02 shall not be incorporated by reference into any registration statement or other document filed by the Company with the SEC, whether made before or after the date of this Current Report on Form 8-K, regardless of any general incorporation language in such filing (or any reference to this Current Report on Form 8-K generally), except as shall be expressly set forth by specific reference in such filing.

Item 8.01 Other Events

On February 12, 2020, the Company issued a press release announcing the Offering. A copy of the press release is attached hereto as Exhibit 99.1. On February 13, 2020, the Company issued a press release announcing it had priced the Offering. A copy of the press release is attached hereto as Exhibit 99.2.

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.