X0306 4 2023-03-01 0 0001557746 Aclaris Therapeutics, Inc. ACRS 0001604457 Walker Neal C/O ACLARIS THERAPEUTICS, INC. 640 LEE ROAD, SUITE 200 WAYNE PA 19087 1 0 0 0 Common Stock 2023-03-01 4 M 0 96150 A 1271913 D Common Stock 2023-03-01 4 M 0 18275 A 1290188 D Common Stock 2023-03-01 4 M 0 24000 A 1314188 D Common Stock 2023-03-02 4 S 0 29000 12.3651 D 1285188 D Common Stock 2023-03-02 4 M 0 18254 A 1303442 D Common Stock 2023-03-03 4 S 0 30240 12.6346 D 1273202 D Restricted Stock Units 2023-03-01 4 M 0 96150 0.00 D Common Stock 96150 0 D Restricted Stock Units 2023-03-01 4 M 0 18275 0.00 D Common Stock 18275 36550 D Restricted Stock Units 2023-03-01 4 M 0 24000 0.00 D Common Stock 24000 72000 D Restricted Stock Units 2023-03-02 4 M 0 18254 0.00 D Common Stock 18254 18254 D Each restricted stock unit represents a contingent right to receive one share of common stock of the issuer. Shares sold to satisfy withholding tax obligations upon the delivery of shares of common stock for restricted stock units that vested on March 1, 2023 pursuant to preexisting sell-to-cover elections. The price reported is a weighted average sales price. The shares were sold in multiple transactions at prices ranging from $11.88 to $12.69, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. Shares sold to satisfy withholding tax obligations upon the delivery of shares of common stock for restricted stock units that vested on March 1, 2023 and March 2, 2023 pursuant to preexisting sell-to-cover elections. The price reported is a weighted average sales price. The shares were sold in multiple transactions at prices ranging from $12.39 to $12.93, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. The shares underlying these restricted stock units were originally scheduled to vest in four equal annual installments beginning on March 1, 2020, subject to the Reporting Person's continuous service with the issuer as of the applicable vesting date. Pursuant to the Letter Agreement dated November 22, 2022 the shares underlying these restricted stock units will cease vesting on December 31, 2023. The shares underlying these restricted stock units were originally scheduled to vest in four equal annual installments beginning on March 1, 2022, subject to the Reporting Person's continuous service with the issuer as of the applicable vesting date. Pursuant to the Letter Agreement dated November 22, 2022 the shares underlying these restricted stock units will cease vesting on December 31, 2023. The shares underlying these restricted stock units were originally scheduled to vest in four equal annual installments beginning on March 1, 2023, subject to the Reporting Person's continuous service with the issuer as of the applicable vesting date. Pursuant to the Letter Agreement dated November 22, 2022 the shares underlying these restricted stock units will cease vesting on December 31, 2023. The shares underlying these restricted stock units were originally scheduled to vest in four equal annual installments beginning on March 2, 2021, subject to the Reporting Person's continuous service with the issuer as of the applicable vesting date. Pursuant to the Letter Agreement dated November 22, 2022 the shares underlying these restricted stock units will cease vesting on December 31, 2023. /s/ Mark Ballantyne, Attorney-in-fact 2023-03-03