FORM 4
☐

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person *
SEIDENBERG BETH C
 2. Issuer Name and Ticker or Trading Symbol
ACELYRIN, Inc. [SLRN] 		5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director __X__ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
(Last)
(First)
(Middle)

C/O ACELYRIN, INC., 4149 LIBERTY CANYON RD.		 3. Date of Earliest Transaction (Month/Day/Year)
05/09/2023
(Street)

AGOURA HILLS, CA 91301
(City)
(State)
(Zip)
4. If Amendment, Date Original Filed(Month/Day/Year)
6. Individual or Joint/Group Filing
(Check applicable line)

__X__ Form Filed by One Reporting Person
_____ Form Filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3)

2. Transaction Date (Month/Day/Year)

2A. Deemed Execution Date, if any (Month/Day/Year)

3. Transaction Code (Instr. 8)

4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)

5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)

6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)

7. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

Amount

(A) or (D)

Price

Common Stock

05/09/2023 C (1)  8,540,729A (1) 8,540,729I

See footnote (2)

Common Stock

05/09/2023 P (3)  1,250,000A $189,790,729I

See footnote (2)

Common Stock

05/09/2023 P (4)  60,000A $1860,000D 


Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security
(Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code
(Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Series A Redeemable Convertible Preferred Stock

 (5) 05/09/2023 C  4,056,795  (5)   (5)

Common Stock (6)

4,056,795 (5) 0 I

See footnote (2)

Series B Redeemable Convertible Preferred Stock

 (5) 05/09/2023 C  2,445,786  (5)   (5)

Common Stock (6)

2,445,786 (5) 0 I

See footnote (2)

Series C Redeemable Convertible Preferred Stock

 (5) 05/09/2023 C  2,038,148  (5)   (5)

Common Stock (6)

2,038,148 (5) 0 I

See footnote (2)

Director Stock Option (right to buy)

 $1805/09/2023 J (6)   23,243  (7) 05/03/2033

Class A Common Stock (6)

23,243 $ 0 0 D 

Director Stock Option (right to buy)

 $1805/09/2023 J (6)  23,243   (7) 05/03/2033

Common Stock (6)

23,243 $ 0 23,243D 

Explanation of Responses:
1.

Represents shares of Common Stock received upon conversion of shares of the reported series of preferred stock on a one-for-one basis without payment of further consideration.

2.

Shares held directly by Westlake BioPartners Fund II, L.P., or Westlake Fund II. Westlake BioPartners GP II, LLC, or Westlake GP II, is the general partner of Westlake Fund II. Westlake GP II may be deemed to have sole voting and dispositive power with regard to the shares held directly by Westlake Fund II. The Reporting Person and Sean E. Harper are the Managing Directors of Westlake GP II and share voting and dispositive power over the shares held by Westlake Fund II, each of whom disclaims beneficial ownership of the shares held by Westlake Fund II except to the extent of such person's pecuniary interest therein, if any.

3.

Represents shares of Common Stock purchased in the Issuer's initial public offering of Common Stock (the "IPO").

4.

Represents shares of Common Stock purchased through a directed share program in the IPO.

5.

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 IPO, all shares of preferred stock automatically converted into shares of Common Stock.

6.

Each share of Class A Common Stock was reclassified into one share of Common Stock immediately prior to the completion of the IPO.

7.

1/36 of the shares subject to the option vest on June 4, 2023, and 1/36 of the shares subject to the option vest in equal monthly installments thereafter, subject to the Reporting Person's continued service.



Signatures

/s/ Mina Kim, Attorney-in-fact

05/11/2023
** Signature of Reporting PersonDate
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