Form 4: ACELYRIN Director Reports Full Share and Option Disposition Following Merger with Alumis

ACELYRIN, Inc. Director Beth Seidenberg has reported the disposition of all her direct and indirect holdings of common stock and stock options in ACELYRIN, Inc. as a result of the company's merger with Alumis, Inc. on May 21, 2025.

Summary

• Beth C. Seidenberg, a Director of ACELYRIN, Inc. (SLRN), reported changes in her beneficial ownership following the merger of ACELYRIN into Alumis, Inc. on May 21, 2025.
• At the effective time of the merger, ACELYRIN became a wholly owned subsidiary of Alumis, Inc.
• Each share of ACELYRIN common stock was converted into the right to receive 0.4814 shares of Alumis voting common stock, with cash in lieu of any fractional shares.
• Ms. Seidenberg disposed of 60,000 directly held shares of ACELYRIN common stock.
• She also disposed of 9,790,729 indirectly held shares of ACELYRIN common stock through Westlake BioPartners Fund II, L.P.
• All outstanding and unexercised ACELYRIN stock options with an exercise price of $18.00 or less were assumed by Alumis and converted into options to purchase Alumis common stock based on the 0.4814 exchange ratio.
• Specifically, 23,243 Director Stock Options with an exercise price of $18.00 and 92,158 Director Stock Options with an exercise price of $4.46 were disposed of as ACELYRIN options and converted into Alumis options.
• Following these transactions, Ms. Seidenberg's beneficial ownership of ACELYRIN common stock and options is 0.

Sentiment

Score: 7

Explanation: The sentiment is positive as it confirms the successful completion of a strategic merger, which typically aims to create value for shareholders. While the reporting person's direct holdings in ACELYRIN are zeroed out, they are converted into holdings in the acquiring entity, Alumis, Inc., indicating a continuation of their equity interest in the combined business.

Positives

• The completion of the merger indicates a successful strategic transaction for ACELYRIN, Inc., transitioning it into a wholly-owned subsidiary of Alumis, Inc.
• The conversion of ACELYRIN stock options into Alumis stock options allows the reporting person to maintain an equity interest in the combined entity, preserving potential future value.

Negatives

• The reporting person no longer holds direct or indirect beneficial ownership in ACELYRIN, Inc. common stock, as the company ceased to be an independent publicly traded entity.

Industry Context

This filing reflects the completion of a significant M&A transaction in the biotechnology or pharmaceutical sector, where ACELYRIN, a publicly traded company, was acquired by Alumis, Inc. Such mergers are common strategies for companies to consolidate assets, pipelines, and market positions, often driven by the desire to achieve synergies or expand therapeutic areas.

Related Party Transactions

• The indirect ownership of shares through Westlake BioPartners Fund II, L.P., where the Reporting Person is a Managing Director of the general partner, Westlake GP II, LLC, constitutes a related party arrangement.
• The Reporting Person disclaims beneficial ownership of these shares except to the extent of their pecuniary interest.

Stakeholder Impact

• Shareholders (ACELYRIN): Their shares were converted into Alumis common stock, indicating a change in their investment vehicle and potentially a new valuation basis.
• Shareholders (Alumis): The merger expands Alumis's asset base and potentially its market position.
• Employees (ACELYRIN): The company is now a wholly-owned subsidiary, which could lead to integration efforts and potential changes in corporate structure or culture.
• Management (ACELYRIN): The reporting person, a director, has had their equity converted, aligning their interests with the new parent company.

Next Steps

• The reporting person's equity interest in the combined entity will now be reflected through holdings in Alumis, Inc. common stock and converted stock options.
• Future filings for this reporting person will likely be related to Alumis, Inc.

Key Dates

Keywords

SEC Form 4, ACELYRIN Inc., SLRN, Alumis Inc., Merger, Acquisition, Beneficial Ownership, Stock Options, Equity Conversion, Director Holdings, Beth C Seidenberg, Westlake BioPartners