aTyr Pharma, Inc. (ATYR) Ownership
ATYR ownership summary
as of October 18, 2026- Institutions
- 36.2% of shares outstanding
- Insiders
- 0.31% of shares outstanding
- Shares outstanding
- 98.1M
- Float
- 97.7M shares available to trade
- Short interest
- 13.19% 12.9M shares short
- Days to cover
- 1.72 short interest up 20.9% vs prior month
- Institutions 36.20%
- Insiders 0.31%
- Other investors 63.49%
ATYR top institutional holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | Federated Hermes Inc | 8.68% | 8.5M | $1.5M | −2.0M (−19.0%) | June 30, 2026 |
| 2 | Vanguard Capital Management, LLC | 3.88% | 3.8M | $662,608 | −4,041 (−0.1%) | June 30, 2026 |
| 3 | Kalehua Capital Management LLC | 3.65% | 3.6M | $622,282 | +3.6M (0.0%) | June 30, 2026 |
| 4 | GSA Capital Partners LLP | 3.52% | 3.5M | $601,146 | +1.8M (+105.1%) | June 30, 2026 |
| 5 | AQR Capital Management LLC | 2.66% | 2.6M | $454,235 | +2.1M (+426.3%) | June 30, 2026 |
| 6 | FMR Inc | 2.52% | 2.5M | $430,027 | −12.2M (−83.2%) | June 30, 2026 |
| 7 | BlackRock Inc | 1.86% | 1.8M | $317,956 | −4.6M (−71.6%) | June 30, 2026 |
| 8 | Jane Street Group LLC | 1.75% | 1.7M | $299,506 | +1.7M (+3,448.9%) | June 30, 2026 |
| 9 | UBS Group AG | 1.56% | 1.5M | $266,420 | −2.3M (−60.4%) | June 30, 2026 |
| 10 | Morgan Stanley - Brokerage Accounts | 1.37% | 1.3M | $233,793 | +118,169 (+9.6%) | June 30, 2026 |
| 11 | Two Sigma Investments LLC | 1.27% | 1.2M | $216,656 | +100,582 (+8.8%) | June 30, 2026 |
| 12 | Citadel Advisors Llc | 1.27% | 1.2M | $216,120 | +1.2M (+2,521.9%) | June 30, 2026 |
| 13 | Geode Capital Management, LLC | 1.20% | 1.2M | $204,801 | −1.2M (−50.7%) | June 30, 2026 |
| 14 | Susquehanna International Group, LLP | 0.76% | 747K | $129,985 | −119,705 (−13.8%) | June 30, 2026 |
| 15 | Millennium Management LLC | 0.67% | 656K | $114,153 | −985,195 (−60.0%) | June 30, 2026 |
| 16 | The Goldman Sachs Group Inc | 0.65% | 641K | $111,570 | +357,972 (+126.4%) | June 30, 2026 |
| 17 | Vanguard Fiduciary Trust Co | 0.59% | 576K | $100,246 | −75,707 (−11.6%) | June 30, 2026 |
| 18 | State Street Corp | 0.50% | 495K | $86,121 | −1.3M (−71.8%) | June 30, 2026 |
| 19 | Marshall Wace Asset Management Ltd | 0.38% | 368K | $64,053 | +230,002 (+166.5%) | June 30, 2026 |
| 20 | XTX Topco Ltd | 0.23% | 227K | $39,442 | +115,255 (+103.4%) | June 30, 2026 |
Value at the latest close. Change = shares bought or sold in the latest quarterly filing (13F). In the top 20, 10 holders added 11.3M shares and 10 cut 24.8M.
ATYR top mutual fund and ETF holders
16 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | Federated Hermes Kaufmann R | 4.45% | 4.4M | $759,908 | −1.2M (−21.8%) | June 30, 2026 |
| 2 | Federated Hermes Kaufmann Small Cap A | 4.14% | 4.1M | $706,664 | −745,589 (−15.5%) | June 30, 2026 |
| 3 | Vanguard MStar Total Stk Mkt Idx Invest | 2.70% | 2.7M | $461,237 | — | August 31, 2026 |
| 4 | Fidelity Select Biotechnology | 1.79% | 1.8M | $305,299 | — | August 31, 2026 |
| 5 | Fidelity Extended Market Index | 0.56% | 554K | $96,340 | +45,597 (+9.0%) | August 31, 2026 |
| 6 | Abante Quant Value FI | 0.47% | 459K | $79,946 | +160,959 (+53.9%) | July 31, 2026 |
| 7 | Fidelity Total Market Index | 0.17% | 168K | $29,252 | — | August 31, 2026 |
| 8 | Fidelity Series Total Market Index | 0.15% | 145K | $25,292 | — | August 31, 2026 |
| 9 | BSF Systematic US Eq Abs Ret A2 USD | 0.10% | 95K | $16,596 | — | December 31, 2025 |
| 10 | Federated Hermes Kaufmann II P | 0.08% | 81K | $14,111 | −36,701 (−31.2%) | June 30, 2026 |
| 11 | Goldman Sachs Absolute Ret Trckr Instl | 0.07% | 66K | $11,490 | +47,732 (+260.8%) | June 30, 2026 |
| 12 | Fidelity ZERO Extended Market Index | 0.07% | 64K | $11,178 | +29,010 (+82.3%) | August 31, 2026 |
| 13 | Vanguard Balanced Index Inv | 0.06% | 57K | $9,877 | — | August 31, 2026 |
| 14 | Fidelity ZERO Total Market Index | 0.04% | 43K | $7,505 | — | August 31, 2026 |
| 15 | Vanguard U.S. Eq Idx £ Acc | 0.03% | 33K | $5,814 | — | August 31, 2026 |
| 16 | Vanguard MStar Inst Ttl StkMktIdxInstlPl | 0.03% | 26K | $4,521 | −20,000 (−43.5%) | August 31, 2026 |
Funds report holdings monthly or quarterly; dates differ by fund.
ATYR insider transactions
latest 5| Date | Name | Transaction | Price | Shares | Value |
|---|---|---|---|---|---|
| 2026-02-04 | Jill Marie Broadfoot | Sell | $0.98 | 1,558 | $1,527 |
| 2026-02-04 | Nancy Denyes | Sell | $0.98 | 1,118 | $1,096 |
| 2026-02-04 | Sanjay Shukla | Sell | $0.98 | 3,745 | $3,670 |
| 2025-10-09 | Paul Schimmel | Buy | $0.94 | 317,999 | $298,919 |
| 2025-10-08 | Paul Schimmel | Buy | $0.90 | 682,001 | $613,801 |
Reported trades by company officers, directors and other filers (including disclosures by members of Congress where EODHD lists them). "—" where the filing gives no share count.
ATYR shares outstanding
Year-end shares outstanding, adjusted for splits.
Who owns ATYR
Institutional investors own 36.2% of aTyr Pharma's shares and insiders 0.31%. The largest holder is Federated Hermes Inc with 8.68% of the shares (8.5M), as of June 30, 2026. Among the top 20 institutions, 10 added shares and 10 reduced their stake in the latest filings. Short interest is 13.19% of the float, or 1.72 days of average trading volume. The share count rose 13,522.0% since 2014.
Related: ATYR analyst forecast, ATYR key metrics. See the ATYR stock overview for the latest quote and news.
ATYR ownership FAQ
Who owns the most aTyr Pharma stock?
The largest shareholders of aTyr Pharma are Federated Hermes Inc (8.68%), Vanguard Capital Management, LLC (3.88%), Kalehua Capital Management LLC (3.65%), GSA Capital Partners LLP (3.52%), AQR Capital Management LLC (2.66%).
What percentage of aTyr Pharma is owned by institutions?
Institutions hold 36.2% of aTyr Pharma's shares outstanding; insiders hold 0.31%.
Which funds own aTyr Pharma?
The largest fund holders of aTyr Pharma are Federated Hermes Kaufmann R (4.45%), Federated Hermes Kaufmann Small Cap A (4.14%), Vanguard MStar Total Stk Mkt Idx Invest (2.70%), Fidelity Select Biotechnology (1.79%), Fidelity Extended Market Index (0.56%).
What is aTyr Pharma's short interest?
12.9M shares of aTyr Pharma were sold short, 13.19% of the float; at the average daily volume it would take 1.72 days to cover.
Are insiders buying or selling aTyr Pharma?
Of the latest 5 reported insider transactions in aTyr Pharma (since October 8, 2025), 2 were purchases and 3 were sales.
How many shares of aTyr Pharma are outstanding?
aTyr Pharma has 98.1M shares outstanding, of which 97.7M are in the public float.