Amendment: SEC Form SCHEDULE 13D/A filed by ACELYRIN INC.

The information set forth in Item 4 of the Schedule 13D is hereby supplemented to include the following information: On May 21, 2025, pursuant to the Agreement and Plan of Merger, dated as of February 6, 2025, as amended on April 20, 2025 (as amended, the "Merger Agreement"), by and among the Issuer, Alumis Inc., a Delaware corporation ("Alumis") and Arrow Merger Sub, Inc., a Delaware corporation and a wholly owned subsidiary of Alumis ("Merger Sub"), the Issuer completed its merger with Merger Sub, whereby Merger Sub merged with and into the Issuer, in accordance with the General Corporation Law of the State of Delaware, with the Issuer continuing as the surviving corporation and as a wholly owned subsidiary of Alumis (the "Merger"). In connection with the Merger, and upon the terms and subject to the conditions set forth in the Merger Agreement, at the effective time of the Merger (the "Effective Time"), each share of Common Stock issued and outstanding was converted into the right to receive 0.4814 shares of voting common stock of Alumis, par value $0.0001 per share, and cash in lieu of any fractional shares. At the Effective Time, each holder of Common Stock outstanding immediately prior to the Effective Time ceased to have any rights as a stockholder of the Issuer other than the right to receive the consideration for such stockholder's shares of Common Stock under the Merger Agreement. In connection with the closing of the Merger, on May 21, 2025, the Issuer (i) notified The Nasdaq Stock Market LLC ("Nasdaq") that the Merger had been completed and (ii) requested that Nasdaq suspend trading of the Common Stock, effective as of the open of business on May 21, 2025, and filed with the SEC a Form 25, Notification of Removal from Listing and/or Registration, to delist all Common Stock from Nasdaq and deregister the Common Stock under Section 12(b) of the Exchange Act. The Issuer also intends to file a Certification and Notice of Termination of Registration on Form 15 with the SEC requesting the termination of registration of the Common Stock under Section 12(g) of the Exchange Act and the suspension of the Issuer's reporting obligations under Sections 13 and 15(d) of the Exchange Act. As a result of the Merger, on May 21, 2025, each of the Reporting Persons ceased to be the beneficial owner of more than five percent of Common Stock.

The information set forth in Item 5(a) of Schedule 13D is hereby amended and restated as follows: The responses of each of the Reporting Persons with respect to Rows 11, 12, and 13 of the cover pages of this Schedule 13D that relate to the aggregate number and percentage of Common Stock (including but not limited to footnotes to such information) are incorporated herein by reference.

The information set forth in Item 5(b) of Schedule 13D is hereby amended and restated as follows: The responses of each of the Reporting Persons with respect to Rows 7, 8, 9, and 10 of the cover pages of this Schedule 13D that relate to the number of Common Stock as to which each of the persons or entities referenced in Item 2 above has sole or shared power to vote or to direct the vote of and sole or shared power to dispose of or to direct the disposition of (including but not limited to footnotes to such information) are incorporated herein by reference. As a result of the Merger, on May 21, 2025, none of the Reporting Persons holds any shares of Common Stock.

The information set forth in Item 5(c) of Schedule 13D is hereby supplemented to incorporate by reference the information set forth in Item 4 above.

On May 21, 2025, each of the Reporting Persons ceased to be the beneficial owner of more than five percent of Common Stock.

99.7 Joint Filing Agreement, dated as of May 23, 2025