---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-25-123707"
form_type: "8-K"
ticker: null
cik: "0001962918"
company_name: "ACELYRIN, Inc."
filed_at: "2025-05-21T23:59:59+00:00"
generated_at: "2026-05-20T22:53:19.141690+00:00"
event_type: "m_and_a"
sentiment: "neutral"
materiality_score: 1.0
calibrated_materiality_score: 1.0
confidence: "high"
source: SEC EDGAR
---

# ACELYRIN completes merger with Alumis, becomes wholly owned subsidiary; stock to be delisted

## Summary
- Merger effective May 21, 2025; each SLRN share converted into 0.4814 shares of Alumis common stock.
- ACELYRIN requests Nasdaq delisting and intends to deregister shares under Exchange Act.
- All ACELYRIN directors and executive officers resigned; replaced by Merger Sub's directors and officers.
- Certificate of incorporation and bylaws amended and restated to those of Merger Sub.
- Outstanding equity awards converted to Alumis awards; options with exercise price >$18.00 cancelled.

## SEC filing metadata
- accession: 0001193125-25-123707
- form_type: 8-K
- cik: 0001962918
- company_name: ACELYRIN, Inc.
- filed_at: 2025-05-21T23:59:59+00:00
- event_type: m_and_a
- sentiment: neutral
- materiality_score: 1.0
- calibrated_materiality_score: 1.0
- confidence: high
- sec_items: 1.02, 2.01, 3.01, 5.01, 5.02, 5.03, 3.03, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1962918/000119312525123707/0001193125-25-123707-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1962918/000119312525123707/d13977d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-25-123707
- JSON: https://secwatch.observer/filing/0001193125-25-123707.json
- Plain text: https://secwatch.observer/filing/0001193125-25-123707.txt

## Key facts
- Executive change
  Henry O. Gosebruch departed as Director at ACELYRIN, Inc..
  - Action: ceased serving
  - Role: Director
  source text: each of Alan Colowick, M.D., M.P.H., Patrick Machado, J.D., Beth Seidenberg, M.D., Bruce C. Cozadd, Dan Becker, M.D., Ph.D., Dawn Svoronos, Lynn Tetrault, J.D., Mina Kim and Henry O. Gosebruch ceased serving as a member of the board of directors of ACELYRIN and each committee thereof.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1962918/000119312525123707/0001193125-25-123707-index.htm
- Executive change
  Bruce C. Cozadd departed as Director at ACELYRIN, Inc..
  - Action: ceased serving
  - Role: Director
  source text: each of Alan Colowick, M.D., M.P.H., Patrick Machado, J.D., Beth Seidenberg, M.D., Bruce C. Cozadd, Dan Becker, M.D., Ph.D., Dawn Svoronos, Lynn Tetrault, J.D., Mina Kim and Henry O. Gosebruch ceased serving as a member of the board of directors of ACELYRIN and each committee thereof.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1962918/000119312525123707/0001193125-25-123707-index.htm
- Executive change
  Patrick Machado, J.D. departed as Director at ACELYRIN, Inc..
  - Action: ceased serving
  - Role: Director
  source text: each of Alan Colowick, M.D., M.P.H., Patrick Machado, J.D., Beth Seidenberg, M.D., Bruce C. Cozadd, Dan Becker, M.D., Ph.D., Dawn Svoronos, Lynn Tetrault, J.D., Mina Kim and Henry O. Gosebruch ceased serving as a member of the board of directors of ACELYRIN and each committee thereof.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1962918/000119312525123707/0001193125-25-123707-index.htm
- Executive change
  Dan Becker, M.D., Ph.D. departed as Director at ACELYRIN, Inc..
  - Action: ceased serving
  - Role: Director
  source text: each of Alan Colowick, M.D., M.P.H., Patrick Machado, J.D., Beth Seidenberg, M.D., Bruce C. Cozadd, Dan Becker, M.D., Ph.D., Dawn Svoronos, Lynn Tetrault, J.D., Mina Kim and Henry O. Gosebruch ceased serving as a member of the board of directors of ACELYRIN and each committee thereof.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1962918/000119312525123707/0001193125-25-123707-index.htm
- Executive change
  Lynn Tetrault, J.D. departed as Director at ACELYRIN, Inc..
  - Action: ceased serving
  - Role: Director
  source text: each of Alan Colowick, M.D., M.P.H., Patrick Machado, J.D., Beth Seidenberg, M.D., Bruce C. Cozadd, Dan Becker, M.D., Ph.D., Dawn Svoronos, Lynn Tetrault, J.D., Mina Kim and Henry O. Gosebruch ceased serving as a member of the board of directors of ACELYRIN and each committee thereof.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1962918/000119312525123707/0001193125-25-123707-index.htm
- Executive change
  Beth Seidenberg, M.D. departed as Director at ACELYRIN, Inc..
  - Action: ceased serving
  - Role: Director
  source text: each of Alan Colowick, M.D., M.P.H., Patrick Machado, J.D., Beth Seidenberg, M.D., Bruce C. Cozadd, Dan Becker, M.D., Ph.D., Dawn Svoronos, Lynn Tetrault, J.D., Mina Kim and Henry O. Gosebruch ceased serving as a member of the board of directors of ACELYRIN and each committee thereof.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1962918/000119312525123707/0001193125-25-123707-index.htm
- Executive change
  Alan Colowick, M.D., M.P.H. departed as Director at ACELYRIN, Inc..
  - Action: ceased serving
  - Role: Director
  source text: each of Alan Colowick, M.D., M.P.H., Patrick Machado, J.D., Beth Seidenberg, M.D., Bruce C. Cozadd, Dan Becker, M.D., Ph.D., Dawn Svoronos, Lynn Tetrault, J.D., Mina Kim and Henry O. Gosebruch ceased serving as a member of the board of directors of ACELYRIN and each committee thereof.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1962918/000119312525123707/0001193125-25-123707-index.htm
- Executive change
  Mina Kim departed as Director at ACELYRIN, Inc..
  - Action: ceased serving
  - Role: Director
  source text: each of Alan Colowick, M.D., M.P.H., Patrick Machado, J.D., Beth Seidenberg, M.D., Bruce C. Cozadd, Dan Becker, M.D., Ph.D., Dawn Svoronos, Lynn Tetrault, J.D., Mina Kim and Henry O. Gosebruch ceased serving as a member of the board of directors of ACELYRIN and each committee thereof.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1962918/000119312525123707/0001193125-25-123707-index.htm
- Executive change
  Dawn Svoronos departed as Director at ACELYRIN, Inc..
  - Action: ceased serving
  - Role: Director
  source text: each of Alan Colowick, M.D., M.P.H., Patrick Machado, J.D., Beth Seidenberg, M.D., Bruce C. Cozadd, Dan Becker, M.D., Ph.D., Dawn Svoronos, Lynn Tetrault, J.D., Mina Kim and Henry O. Gosebruch ceased serving as a member of the board of directors of ACELYRIN and each committee thereof.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1962918/000119312525123707/0001193125-25-123707-index.htm
- Governance Changes
  ACELYRIN, Inc.: Bylaws amended and restated in connection with merger, to read as Merger Sub's bylaws.
  - Change: bylaw amendment
  source text: Pursuant to the terms of the Merger Agreement, as of the Effective Time, the certificate of incorporation and bylaws of ACELYRIN were amended and restated to read in their entirety as the certificate of incorporation and bylaws, respectively, of Merger Sub in effect immediately prior to the Effective Time.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1962918/000119312525123707/0001193125-25-123707-index.htm
- Governance Changes
  ACELYRIN, Inc.: Certificate of incorporation amended and restated in connection with merger, to read as Merger Sub's certificate of incorporation.
  - Change: charter amendment
  source text: Pursuant to the terms of the Merger Agreement, as of the Effective Time, the certificate of incorporation and bylaws of ACELYRIN were amended and restated to read in their entirety as the certificate of incorporation and bylaws, respectively, of Merger Sub in effect immediately prior to the Effective Time.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1962918/000119312525123707/0001193125-25-123707-index.htm
- M&A Transactions
  ACELYRIN, Inc. underwent a change of control involving Alumis Inc. for 0.4814 shares of Alumis Common Stock per share of ACELYRIN Common Stock (closed 2025-05-21).
  - Action: change of control
  - Counterparty: Alumis Inc.
  - Consideration: 0.4814 shares of Alumis Common Stock per share of ACELYRIN Common Stock
  - Closing: 2025-05-21
  source text: April 21, 2025, ACELYRIN, Inc., a Delaware corporation (“ ACELYRIN ”), entered into an Agreement and Plan of Merger, dated as of February 6, 2025, which was subsequently amended on April 20, 2025 (as amended, the “ Merger Agreement ”), by and among ACELYRIN, Alumis Inc., a Delaware corporation (“ Alumis ”), and Arrow Merger Sub, Inc., a Delaware corporation and a direct wholly owned subsidiary of Alumis (“ Merger Sub ”).
  evidence_url: https://www.sec.gov/Archives/edgar/data/1962918/000119312525123707/0001193125-25-123707-index.htm

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.