Transaction Details

Footnotes

On February 6, 2025, ACELYRIN, Inc., a Delaware corporation (the "Company"), entered into an Agreement and Plan of Merger (as amended on April 20, 2025, the "Merger Agreement") with Alumis, Inc., a Delaware corporation ("Parent"), and Arrow Merger Sub, Inc., a Delaware corporation and wholly owned subsidiary of Parent ("Merger Sub"). Pursuant to the Merger Agreement, on May 21, 2025, Merger Sub merged with and into the Company (the "Merger"), with the Company surviving as a wholly owned subsidiary of Parent. At the effective time of the Merger (the "Effective Time"), each share of common stock, par value $0.00001 per share, of the Company issued and outstanding was converted into the right to receive 0.4814 (the "Exchange Ratio") shares of voting common stock of Parent, par value $0.0001 per share ("Parent Common Stock"), and cash in lieu of any fractional shares. | 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 is the Managing Director of Westlake GP II and has sole voting and dispositive power over the shares held by Westlake Fund II, and disclaims beneficial ownership of the shares held by Westlake Fund II except to the extent of the Reporting Person's pecuniary interest therein, if any. | 1/36 of the shares subject to the option vested 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. | Pursuant to the Merger Agreement, at the Effective Time each stock option that was outstanding and unexercised immediately prior to the Effective Time with a per share exercise price of $18.00 or less was assumed by Parent and converted into an option to purchase a number of shares of Parent Common Stock equal to (i) the number of shares subject to the option immediately prior to the Effective Time, multiplied by (ii) the Exchange Ratio, with any fractional shares rounded down to the nearest whole share, which stock option shall have an exercise price equal to (i) the per share exercise price for shares subject to the corresponding Company stock option immediately prior to the Effective Time, divided by (ii) the Exchange Ratio, rounded up to the nearest whole cent. | All of the shares subject to the option vest on the earlier of (i) June 7, 2025, or (ii) the day immediately preceding the next annual meeting of stockholders following the grant date of the option, subject to the Reporting Person's continued service as a director through the vesting date.