Stock ownership · SEC 13F · Q1 2025

ACELYRIN INC

Institutional ownership of ACELYRIN INC (CUSIP 00445A100) - who holds it, how concentrated it is, and what moved last quarter.

$362K
Reported value
2
Institutions
100%
Top-5 share

The verdict

2 institutions report $362K of ACELYRIN INC positions as of Q1 2025, with ownership heavily concentrated in a handful of holders.

2
institutions hold it
$362K
reported 13F value
100%
held by top 5

Based on long positions reported to the SEC as of Q1 2025; 13F omits shorts, options and non-US holdings.

How 13F ownership is computed · All tracked stocks · Concentration rankings

SEC Form 13F-HR ownership desk

CUSIP 00445A100 · Q1 2025 $0M reported

VALUE-TRACE · HOLDERS-FOCUS · CONC-DOM · PHOTO-UNK · ACTIVITY-LIGHT · BOOK-SHORT

  • VALUE-TRACE $0.4M
  • HOLDERS-FOCUS 2 filers
  • CONC-DOM 100% top-5
  • PHOTO-UNK No peer
  • ACTIVITY-LIGHT 2 new
  • BOOK-SHORT 3Q history

Read with: Ownership concentration guide - ACELYRIN INC's top-five holders account for 100% of reported value — read concentration before treating any single filer as a signal.

Top Institutional Holders

# Institution Shares Value Share of reported
1 RHUMBLINE ADVISERS 102,174 $252K 69.8%
2 STRS OHIO 44,300 $109K 30.2%

Investment Discretion

SEC Form 13F requires each institutional filer to report whether it exercises sole or shared discretion over a position. Among ACELYRIN INC's reported holders for Q1 2025, by reported value:

Sole discretion (SOLE)
100.0%

Latest Quarter Activity · Q1 2025

New positions (2)

RHUMBLINE ADVISERS $252K
STRS OHIO $109K

Frequently Asked Questions

How many institutions hold ACELYRIN INC?▼
ACELYRIN INC is held by 2 institutional investors per the latest SEC Form 13F filings as of Q1 2025.
What is the total institutional value of ACELYRIN INC?▼
Institutions report $362K of ACELYRIN INC as of Q1 2025.
How concentrated is ownership of ACELYRIN INC?▼
The top five institutional holders account for 100% of the reported institutional value in ACELYRIN INC, making ownership heavily concentrated in a handful of holders.
Who is the largest institutional holder of ACELYRIN INC?▼
RHUMBLINE ADVISERS is the largest reported holder of ACELYRIN INC with $252K across 102,174 shares as of Q1 2025.

Source: U.S. Securities and Exchange Commission (SEC) - EDGAR Form 13F-HR institutional holdings filings · Q1 2025 13F-HR discloses long US-listed equity positions of managers with $100M+ qualifying assets, filed within 45 days of period end. Short positions and most derivatives are not disclosed.

PlainFundData is rendered directly from SEC EDGAR Form 13F-HR institutional holdings filings, no number is typed in by an editor. Holder lists, concentration, and reported value on this page are aggregated live from those 13F-HR extracts. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2026-05-16.