Equillium, Inc.

Our Board of Directors has unanimously approved a series of alternate amendments to our Amended and Restated Certificate of Incorporation, which would:

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effect a reverse stock split (“Reverse Stock Split”) of all issued and outstanding shares of our common stock, at a ratio ranging from 1-for-2 to 1-for-20, inclusive.

Accordingly, effecting a Reverse Stock Split would reduce the number of outstanding shares of our common stock. The effectiveness of any one of these amendments and the abandonment of the other amendments, or the abandonment of all of these amendments, will be determined by our Board of Directors following the Annual Meeting and prior to December 31, 2026. Our Board of Directors has recommended that these proposed amendments be presented to our stockholders for approval.

Our stockholders are being asked to approve these proposed amendments pursuant to Proposal 2, and to grant authorization to our Board of Directors to determine, at its option, whether to implement a Reverse Stock Split, including its specific timing and ratio.

Should we receive the required stockholder approvals for Proposal 2, our Board of Directors will have the sole authority to elect, at any time on or prior to December 31, 2026 and without the need for any further action on the part of our stockholders, whether to effect a Reverse Stock Split and the number of whole shares of our common stock, between and including two (2) and twenty (20), that will be combined into one share of our common stock.

Notwithstanding approval of Proposal 2 by our stockholders, our Board of Directors may, at its sole option, abandon the proposed amendments and determine prior to the effectiveness of any filing with the Secretary of State of the State of Delaware not to effect any Reverse Stock Split, as permitted under Section 242(c) of the General Corporation Law of the State of Delaware. If our Board of Directors does not implement a Reverse Stock Split on or prior to December 31, 2026, stockholder approval would again be required prior to implementing any Reverse Stock Split.

By approving Proposal 2, our stockholders will: (a) approve a series of alternate amendments to our Amended and Restated Certificate of Incorporation pursuant to which any whole number of outstanding shares of common stock between and including two (2) and twenty (20) could be combined into one share of common stock; and (b) authorize our Board of Directors to file only one such amendment, as determined by the Board at its sole option, and to abandon each amendment not selected by the Board. Our Board of Directors may also elect not to undertake any Reverse Stock Split and therefore abandon all amendments.