Equillium, Inc.

After the effective date of any Reverse Stock Split that our Board of Directors elects to implement, each stockholder will own a reduced number of shares of common stock. However, any Reverse Stock Split will affect all of our stockholders uniformly and will not affect any stockholder’s percentage ownership interests in Equillium, except to the extent that the Reverse Stock Split results in any of our stockholders owning a fractional share as described below. Voting rights and other rights and preferences of the holders of our common stock will not be affected by a Reverse Stock Split (other than as a result of the payment of cash in lieu of fractional shares). For example, a holder of 2% of the voting power of the outstanding shares of our common stock immediately prior to a Reverse Stock Split would continue to hold 2% (assuming there is no impact as a result of the payment of cash in lieu of issuing fractional shares) of the voting power of the outstanding shares of our common stock immediately after such Reverse Stock Split. The number of stockholders of record will not be affected by a Reverse Stock Split (except to the extent that any stockholder holds only a fractional share interest and receives cash for such interest after such Reverse Stock Split).

The principal effects of a Reverse Stock Split will be that:

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depending on the Reverse Stock Split ratio selected by the Board, each [two to twenty shares] of our common stock owned by a stockholder will be combined into one new share of our common stock;

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no fractional shares of common stock will be issued in connection with any Reverse Stock Split; instead, holders of common stock who would otherwise receive a fractional share of common stock pursuant to the Reverse Stock Split will receive cash in lieu of the fractional share as explained more fully below;

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the Reverse Stock Split will result in an effective increase in the authorized number of shares of our common stock available for issuance;

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based upon the Reverse Stock Split ratio selected by the Board, proportionate adjustments will be made to the per share exercise price and/or the number of shares issuable upon the exercise or vesting of all then outstanding stock options, restricted stock units and warrants (if any), which will result in a proportional decrease in the number of shares of our common stock reserved for issuance upon exercise or vesting of such stock options, restricted stock units and warrants, and, in the case of stock options and warrants, a proportional increase in the exercise price of all such stock options and warrants; and

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the number of shares then reserved for issuance under our equity compensation plans will be reduced proportionately based upon the Reverse Stock Split ratio selected by the Board.

The following table contains approximate information, based on share information as of April 1, 2026, relating to our authorized and outstanding common stock based on the proposed Reverse Stock Split ratios (without giving effect to the treatment of fractional shares):

After the effective date of any Reverse Stock Split that our Board of Directors elects to implement, our common stock would have a new committee on uniform securities identification procedures (CUSIP) number, a number used to identify our common stock.

Our common stock is currently registered under Section 12(b) of the Exchange Act and we are subject to the periodic reporting and other requirements of the Exchange Act. The implementation of any proposed Reverse Stock Split will not affect the registration of our common stock under the Exchange Act. Our common stock would continue to be listed on The Nasdaq Capital Market under the symbol “EQ” immediately following the Reverse Stock Split, although it is likely that Nasdaq would add the letter “D” to the end of the trading symbol for a period of twenty trading days after the effective date of the Reverse Stock Split to indicate that the Reverse Stock Split had occurred.