X0306 4 2021-10-06 0 0001746466 Equillium, Inc. EQ 0001746808 Connelly Stephen 2223 AVENIDA DE LA PLAYA SUITE 105 LA JOLLA CA 92037 1 1 0 0 Chief Scientific Officer Common Stock 2021-10-06 4 M 0 5625 4.75 A 998625 D Common Stock 2021-10-06 4 S 0 5625 7.0077 D 993000 D Common Stock 2021-10-06 4 M 0 2467 2.80 A 995467 D Common Stock 2021-10-06 4 S 0 2467 7.0076 D 993000 D Employee Stock Option (right to buy) 4.75 2021-10-06 4 M 0 5625 0.00 D 2020-12-10 2029-12-09 Common Stock 5625 0 D Employee Stock Option (right to buy) 2.80 2021-10-06 4 M 0 2467 0.00 D 2021-05-19 2030-05-18 Common Stock 2467 0 D The transactions reported on this form were effected pursuant to a 10b5-1 trading plan adopted by the filer on March 31, 2021. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $7.05 to $7.00, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this Form 4. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $7.06 to $7.00, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this Form 4. This option, representing a right to purchase twenty-five percent of the shares subject to the grant, became exercisable on December 10, 2020, which was the first anniversary of the date on which the option was granted, the remaining portion of this option vests in 36 equal monthly installments thereafter. This option, representing a right to purchase twenty-five percent of the shares subject to the grant, became exercisable on May 19, 2021, which was the first anniversary of the date on which the option was granted, the remaining portion of this option vests in 36 equal monthly installments thereafter. Jason A. Keyes, Attorney -in-Fact for Stephen Connelly 2021-10-07