X0508 4 2024-01-01 0 0001557746 Aclaris Therapeutics, Inc. ACRS 0001957554 Balthaser Kevin C/O ACLARIS THERAPEUTICS, INC. 701 LEE ROAD, SUITE 103 WAYNE PA 19087 0 1 0 0 Chief Financial Officer 0 Common Stock 2024-01-01 4 M 0 7500 A 22961 D Common Stock 2024-01-01 4 F 0 2536 1.05 D 20425 D Restricted Stock Units 2024-01-01 4 M 0 7500 0.00 D Common Stock 7500 22500 D Each restricted stock unit represents a contingent right to receive one share of common stock of the issuer. The transaction reported represents the withholding of shares by the issuer to satisfy the Reporting Person's tax withholding obligations in connection with the vesting and settlement of restricted stock units described in this Form 4. On February 1, 2023, the Reporting Person was granted 30,000 restricted stock units. The shares underlying these restricted stock units vest in four equal installments on the first, second, third and fourth anniversaries of January 1, 2023, subject to the Continuous Service of the Reporting Person (as defined in the Plan) as of each such date. /s/ Mark Ballantyne, Attorney-in-Fact 2024-01-03