SEC FORM 3

SEC Form 3

FORM 3

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

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
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

(Last)

(First)

(Middle)

C/O ACELYRIN, INC.

4149 LIBERTY CANYON RD.

(Street)

AGOURA HILLS

91301

(City)

(State)

(Zip)

2. Date of Event Requiring Statement (Month/Day/Year)
05/04/2023

3. Issuer Name and Ticker or Trading Symbol
ACELYRIN, Inc. [ SLRN ]

4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

5. If Amendment, Date of 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 Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
1. Title of Derivative Security (Instr. 4)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
Series A Redeemable Convertible Preferred Stock	⁽¹⁾	⁽¹⁾	Class A Common Stock⁽²⁾	4,056,795	⁽¹⁾	I	See footnote⁽³⁾
Series B Redeemable Convertible Preferred Stock	⁽¹⁾	⁽¹⁾	Class A Common Stock⁽²⁾	2,445,786	⁽¹⁾	I	See footnote⁽³⁾
Series C Redeemable Convertible Preferred Stock	⁽¹⁾	⁽¹⁾	Class A Common Stock⁽²⁾	2,038,148	⁽¹⁾	I	See footnote⁽³⁾

Explanation of Responses:

1. Each share of preferred stock is convertible into one share of Class A Common Stock or, subject to and in accordance with certain provisions set forth in the Issuer's certificate of incorporation, Class B 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 will automatically convert into shares of Common Stock.

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

3. 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.

Remarks:

Exhibit 24 - Power of Attorney

	/s/ Mina Kim, Attorney-in-fact	05/04/2023
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 5 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.