Amendment to Current Report (Form 8-K/A)

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K/A

(Amendment No. 1)

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 30, 2025

Equillium, Inc.

(Exact name of Registrant as Specified in Its Charter)

Delaware	001-38692	82-1554746
(State or Other Jurisdiction of Incorporation)	(Commission File Number)	(IRS Employer Identification No.)

2223 Avenida de la Playa Suite 105 La Jolla, CA		92037
(Address of Principal Executive Offices)		(Zip Code)

Registrant's Telephone Number, Including Area Code: (858) 240-1200

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 (see General Instruction A.2. below):

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

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

Title of each class		Trading Symbol(s)		Name of each exchange on which registered
Common Stock, par value $0.0001 per share		EQ		The NasdaqCapital Market

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. ☐

Explanatory Note

On October 6, 2025, Equillium, Inc. (the "Company") filed a Current Report on Form 8-K (the "Original Form 8-K") with the Securities and Exchange Commission to report the approval of the engagement of Crowe LLP ("Crowe") as the Company's independent registered public accounting firm for the fiscal year ending December 31, 2025, subject to the execution of an engagement letter and completion of Crowe's standard client acceptance procedures. This Amendment No. 1 to Current Report on Form 8-K/A amends the Original Form 8-K to report the specific date of the engagement of Crowe and to provide the disclosures required by Item 304(a)(2) of Regulation S-K.

Item 4.01 Changes in Registrant's Certifying Accountant.

As previously disclosed in the Original Form 8-K, theaudit committee of the Company's Board of Directors previously approved the appointment of Crowe LLP ("Crowe"), an independent registered public accounting firm, to serve as the Company's independent registered public accounting firm for the fiscal year ending December 31, 2025. The Company's engagement of Crowe remained subject to the completion of Crowe's client acceptance procedures and execution of an engagement letter. On October 21, 2025, Crowe confirmed that such client acceptance procedures were complete, and the Company and Crowe executed an engagement letter to engage Crowe as the Company's independent registered public accounting firm.

During the two most recent fiscal years ended December 31, 2024 and December 31, 2023 and the subsequent interim period through October 21, 2025, the effective date of Crowe's appointment, neither the Company, nor any party on behalf of the Company, consulted with Crowe regarding either (i) the application of accounting principles to a specific completed or proposed transaction, the type of audit opinion that might be rendered on the Company's financial statements, or other written or oral information provided that was an important factor considered by the Company in reaching a decision as to an accounting, auditing, or financial reporting issue or (ii) any matter that was either the subject of a disagreement, as that item is defined in Item 304(a)(1)(iv) of Regulation S-K and the related instructions to Item 304 of Regulation S-K, or a "reportable event", as that term is defined in Item 304(a)(1)(v) of Regulation S-K.

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.

	EQUILLIUM, INC.
Date: October 24, 2025	By:/s/ Bruce D. Steel
	Bruce D. Steel
	Chief Executive Officer