X0407 4 2023-05-09 0 0001962918 ACELYRIN, Inc. SLRN 0001725092 Lin Shao-Lee C/O ACELYRIN, INC. 4149 LIBERTY CANYON RD. AGOURA HILLS CA 91301 1 1 0 0 Chief Executive Officer 0 Common Stock 2023-05-09 4 C 0 1161747 A 1161747 I See footnote Class A Common Stock 2023-05-09 4 J 0 1107213 0.00 D 0 D Common Stock 2023-05-09 4 J 0 1107213 0.00 A 1107213 D Common Stock 2023-05-09 4 F 0 337179 24.69 D 770034 D Class A Common Stock 2023-05-09 4 J 0 677813 0.00 D 0 I See footnote Common Stock 2023-05-09 4 J 0 677813 0.00 A 677813 I See footnote Class A Common Stock 2023-05-09 4 J 0 354969 0.00 D 0 I See footnote Common Stock 2023-05-09 4 J 0 354969 0.00 A 354969 I See footnote Class A Common Stock 2023-05-09 4 J 0 354969 0.00 D 0 I See footnote Common Stock 2023-05-09 4 J 0 354969 0.00 A 354969 I See footnote Class A Common Stock 2023-05-09 4 J 0 349898 0.00 D 0 I See footnote Common Stock 2023-05-09 4 J 0 349898 0.00 A 349898 I See footnote Class A Common Stock 2023-05-09 4 J 0 5070 0.00 D 0 I See footnote Common Stock 2023-05-09 4 J 0 5070 0.00 A 5070 I See footnote Series B Redeemable Convertible Preferred Stock 2023-05-09 4 C 0 978314 D Common Stock 978314 0 I See footnote Series C Redeemable Convertible Preferred Stock 2023-05-09 4 C 0 183433 D Common Stock 183433 0 I See footnote Employee Stock Option (right to buy) 18.00 2023-05-09 4 J 0 774788 0.00 D 2033-05-03 Class A Common Stock 774788 0 D Employee Stock Option (right to buy) 18.00 2023-05-09 4 J 0 774788 0.00 A 2033-05-03 Common Stock 774788 774788 D Each share of preferred stock is convertible into one share of Common Stock and has no expiration date. Immediately prior to the completion of the Issuer's initial public offering of Common Stock (the "IPO"), all shares of preferred stock automatically converted into shares of Common Stock. Shares held directly by Woodland Hills Partners LLC, for which the Reporting Person serves as a managing member. Each share of Class A Common Stock was reclassified into one share of Common Stock immediately prior to the completion of the IPO. Represents Restricted Stock Units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Common Stock upon settlement. Represents shares that have been withheld by the Issuer to satisfy the income tax withholding obligations in connection with the net settlement of RSUs, and not a discretionary sale by the Reporting Person. The Common Stock settled and RSUs held by the Reporting Person remain subject to the terms of a lock-up agreement by and between the Reporting Person and certain underwriters of the IPO. Represents 303,237 shares of Common Stock and 466,797 RSUs after the net settlement of vested RSUs into shares of Common Stock upon the completion of the IPO. The remaining RSUs will continue to settle into shares of Common Stock as they vest thereafter, subject to the Reporting Person's continued service. Shares held directly by Shao-Lee Lin, Trustee of the Shao-Lee Lin Trust u/a/d September 23, 2005, for which the Reporting Person serves as trustee. Shares held directly by Shao-Lee Lin 2020 Gift Trust Dtd 7/16/20, for which the Reporting Person's spouse serves as trustee. Shares held directly by Lin Family 2020 Gift Trust Dtd 7/16/20, for which the Reporting Person's spouse shares voting and investment power. Shares held directly by Susie Jun 2020 Gift Trust dtd 7/16/20, for which the Reporting Person serves as trustee. Shares held directly by Susie Jun, Trustee of the Susie Jun Trust U/A/D September 23, 2005, for which the Reporting Person's spouse serves as trustee. 1/4 of the shares subject to the option vest on May 4, 2024, and 1/48 of the shares subject to the option vest in equal monthly installments thereafter, subject to the Reporting Person's continued service. /s/ Mina Kim, Attorney-in-fact 2023-05-11