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) October 16, 2018

Equillium, Inc.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (858) 412-5302

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligations of the registrant under any of the following provisions:

Indicate by check mark whether the registrant is an emerging growth company as defined in 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 3.02 Unregistered Sales of Equity Securities.

In connection with the closing of the initial public offering of shares of common stock of Equillium, Inc. (the “Company”), which occurred on October 16, 2018 (the “IPO”), the Company issued (i) an aggregate of 878,834 shares of its common stock as a result of the automatic conversion of $9.4 million of aggregate principal amount, plus accrued interest thereon, underlying convertible promissory notes and (ii) 228,060 shares of its common stock to Biocon SA pursuant to certain anti-dilution rights that were satisfied in full upon such issuance.

Item 5.03 Amendments to Articles of Incorporation or Bylaws; Change in Fiscal Year.

Amendment and Restatement of Certificate of Incorporation

On October 16, 2018, the Company filed an amended and restated certificate of incorporation (the “Restated Certificate”) with the Secretary of State of the State of Delaware in connection with the closing of the IPO. The Company’s board of directors and stockholders previously approved the Restated Certificate effective as of immediately prior to the closing of the IPO.

A copy of the Restated Certificate is furnished herewith as Exhibit 3.1 and is incorporated herein by reference.

Amendment and Restatement of Bylaws

Effective as of October 16, 2018, the Company adopted amended and restated bylaws (the “Restated Bylaws”) in connection with the closing of the IPO. The Company’s board of directors and stockholders previously approved the Restated Bylaws effective as of and contingent upon the closing of the IPO.

A copy of the Restated Bylaws is furnished herewith as Exhibit 3.2 and is incorporated herein by reference.

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.