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* Westlake BioPartners Fund II, L.P. (Last) (First) (Middle) C/O WESTLAKE BIOPARTNERS, LLC 3075 TOWNSGATE RD., SUITE 140 (Street) WESTLAKE VILLAGE CA 91361 (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) 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) Form filed by One Reporting Person X 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)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Series A Redeemable Convertible Preferred Stock	(1)	(1)	Class A Common Stock(2)	4,056,795	(1)	D(3)(4)
Series B Redeemable Convertible Preferred Stock	(1)	(1)	Class A Common Stock(2)	2,445,786	(1)	D(3)(4)
Series C Redeemable Convertible Preferred Stock	(1)	(1)	Class A Common Stock(2)	2,038,148	(1)	D(3)(4)

1. Name and Address of Reporting Person* Westlake BioPartners Fund II, L.P. (Last) (First) (Middle) C/O WESTLAKE BIOPARTNERS, LLC 3075 TOWNSGATE RD., SUITE 140 (Street) WESTLAKE VILLAGE CA 91361 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Westlake BioPartners GP II, LLC (Last) (First) (Middle) C/O WESTLAKE BIOPARTNERS, LLC 3075 TOWNSGATE RD., SUITE 140 (Street) WESTLAKE VILLAGE CA 91361 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Harper Sean E (Last) (First) (Middle) C/O WESTLAKE BIOPARTNERS, LLC 3075 TOWNSGATE RD., SUITE 140 (Street) WESTLAKE VILLAGE CA 91361 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

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. Beth C. Seidenberg 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.

4. This report on Form 3 is jointly filed by Westlake Fund II, Westlake GP II and Sean E. Harper. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of such person's or entity's pecuniary interest therein, if any. Westlake Fund II has designated a representative, Beth C. Seidenberg, a Managing Director of Westlake GP II, to serve on the Issuer's board of directors. This report shall not be deemed an admission that any such entity or person is a beneficial owner of such securities for the purposes of Section 16 of the Exchange Act, or for any other purpose.

Remarks:

Exhibit 24 - Power of Attorney

	/s/ Jennifer L. Kercher, 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).
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