X0508 4 2024-02-01 0 0001557746 Aclaris Therapeutics, Inc. ACRS 0001781549 Loerop James C/O ACLARIS THERAPEUTICS, INC. 701 LEE ROAD, SUITE 103 WAYNE PA 19087 0 1 0 0 Chief Business Officer 0 Common Stock 2024-02-01 4 M 0 11250 A 32938 D Common Stock 2024-02-01 4 F 0 3853 1.20 D 29085 D Common Stock 2024-02-01 4 M 0 7500 A 36585 D Common Stock 2024-02-01 4 F 0 2568 1.20 D 34017 D Restricted Stock Units 2024-02-01 4 M 0 11250 0.00 D Common Stock 11250 22500 D Restricted Stock Unit 2024-02-01 4 M 0 7500 0.00 D Common Stock 7500 22500 D Employee Stock Option (Right to Buy) 1.20 2024-02-01 4 A 0 206500 0.00 A 2034-01-31 Common Stock 206500 206500 D Restricted Stock Units 2024-02-01 4 A 0 59000 0.00 A Common Stock 59000 59000 D Restricted Stock Units 2024-02-01 4 A 0 147500 0.00 A Common Stock 147500 147500 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. The shares underlying these restricted stock units vest in four equal installments on the first, second, third and fourth anniversaries of February 1, 2022, subject to the Continuous Service (as defined in the Plan) of the Reporting Person as of each such date. The shares underlying these restricted stock units vest in four equal installments on the first, second, third and fourth anniversaries of February 1, 2023, subject to the Continuous Service (as defined in the Plan) of the Reporting Person as of each such date. Exercisable with respect to 25% of the shares subject to the option vesting in four equal installments on the first, second, third and fourth anniversaries of February 1, 2024, subject to the Continuous Service (as defined in the Plan) of the Reporting Person as of each such date. The shares underlying these restricted stock units vest in four equal installments on the first, second, third and fourth anniversaries of February 1, 2024, subject to the Continuous Service (as defined in the Plan) of the Reporting Person as of each such date. 50% of the shares underlying these restricted stock units vest on each of December 31, 2024 and December 31, 2025, subject to the Continuous Service (as defined in the Plan) of the Reporting Person as of each such date. /s/ Mark Ballantyne, Attorney-in-Fact 2024-02-05