Atossa Therapeutics, Inc. (ATOS) Ownership
ATOS ownership summary
as of October 18, 2026- Institutions
- 13.6% of shares outstanding
- Insiders
- 1.85% of shares outstanding
- Shares outstanding
- 10.0M
- Float
- 9.9M shares available to trade
- Short interest
- 7.90% 788K shares short
- Days to cover
- 13.35 short interest up 3.4% vs prior month
- Institutions 13.56%
- Insiders 1.85%
- Other investors 84.60%
ATOS top institutional holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | Vanguard Capital Management, LLC | 3.62% | 362K | $1.1M | +12,651 (+3.6%) | June 30, 2026 |
| 2 | Ameriprise Financial Inc | 2.59% | 258K | $751,461 | +3,100 (+1.2%) | June 30, 2026 |
| 3 | BlackRock Inc | 1.65% | 164K | $478,282 | +31,189 (+23.4%) | June 30, 2026 |
| 4 | Renaissance Technologies Corp | 1.32% | 132K | $384,245 | +23,036 (+21.1%) | June 30, 2026 |
| 5 | Geode Capital Management, LLC | 0.93% | 92K | $268,832 | −4,679 (−4.8%) | June 30, 2026 |
| 6 | UBS Group AG | 0.83% | 83K | $240,424 | −9,414 (−10.2%) | June 30, 2026 |
| 7 | Jane Street Group LLC | 0.57% | 57K | $164,712 | +56,602 (0.0%) | June 30, 2026 |
| 8 | Vanguard Fiduciary Trust Co | 0.53% | 53K | $153,017 | +348 (+0.7%) | June 30, 2026 |
| 9 | Millennium Management LLC | 0.47% | 47K | $135,338 | −20,231 (−30.3%) | June 30, 2026 |
| 10 | State Street Corp | 0.40% | 40K | $115,705 | — | June 30, 2026 |
| 11 | Northern Trust Corp | 0.20% | 20K | $58,925 | +1,025 (+5.3%) | June 30, 2026 |
| 12 | Susquehanna International Group, LLP | 0.16% | 16K | $45,320 | +15,574 (0.0%) | June 30, 2026 |
| 13 | Morgan Stanley - Brokerage Accounts | 0.12% | 12K | $35,924 | −3,857 (−23.8%) | June 30, 2026 |
| 14 | Vanguard Global Advisers, LLC | 0.03% | 3,089 | $8,989 | — | June 30, 2026 |
| 15 | JONES FINANCIAL COMPANIES LLLP | 0.02% | 2,061 | $5,998 | — | June 30, 2026 |
| 16 | Royal Bank of Canada | 0.02% | 1,994 | $5,803 | +1,350 (+209.6%) | June 30, 2026 |
| 17 | Mcf Advisors, LLC | 0.01% | 1,066 | $3,102 | +1,066 (0.0%) | June 30, 2026 |
| 18 | Mercer Global Advisors Inc. | 0.01% | 666 | $1,938 | +666 (0.0%) | June 30, 2026 |
| 19 | Advisor Group Holdings, Inc. | 0.01% | 587 | $1,708 | — | June 30, 2026 |
| 20 | JPMorgan Chase & Co | <0.01% | 390 | $1,135 | +7 (+1.8%) | June 30, 2026 |
Value at the latest close. Change = shares bought or sold in the latest quarterly filing (13F). In the top 20, 12 holders added 147K shares and 4 cut 38K.
ATOS top mutual fund and ETF holders
12 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | Vanguard MStar Total Stk Mkt Idx Invest | 2.57% | 256K | $745,359 | — | August 31, 2026 |
| 2 | Columbia Small Cap Value Discv A | 1.93% | 193K | $561,336 | −8,535 (−4.2%) | August 31, 2026 |
| 3 | Fidelity Extended Market Index | 0.45% | 45K | $130,156 | −240 (−0.5%) | August 31, 2026 |
| 4 | Abante Quant Value FI | 0.40% | 40K | $116,973 | — | August 31, 2026 |
| 5 | Columbia VP Small Cap Value Discovery 1 | 0.34% | 34K | $98,504 | −1,933 (−5.4%) | August 31, 2026 |
| 6 | Fidelity Total Market Index | 0.14% | 14K | $41,852 | — | August 31, 2026 |
| 7 | Fidelity Series Total Market Index | 0.13% | 13K | $36,791 | — | August 31, 2026 |
| 8 | Vanguard Balanced Index Inv | 0.07% | 6,539 | $19,028 | — | August 31, 2026 |
| 9 | Fidelity Nasdaq Composite Index | 0.05% | 4,908 | $14,282 | — | August 31, 2026 |
| 10 | Vanguard U.S. Eq Idx £ Acc | 0.03% | 3,089 | $8,989 | — | August 31, 2026 |
| 11 | 1290 VT Micro Cap K | 0.02% | 1,986 | $5,779 | — | August 31, 2026 |
| 12 | BlackRock Diversified Equity Alpha Inst | 0.01% | 952 | $2,770 | — | July 31, 2026 |
Funds report holdings monthly or quarterly; dates differ by fund.
ATOS insider transactions
latest 1| Date | Name | Transaction | Price | Shares | Value |
|---|---|---|---|---|---|
| 2025-05-21 | Steven C Quay | Buy | $13.20 | 749 | $9,887 |
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.
ATOS shares outstanding
Year-end shares outstanding, adjusted for splits.
Who owns ATOS
Institutional investors own 13.6% of Atossa Therapeutics's shares and insiders 1.85%. The largest holder is Vanguard Capital Management, LLC with 3.62% of the shares (362K), as of June 30, 2026. Among the top 20 institutions, 12 added shares and 4 reduced their stake in the latest filings. Short interest is 7.90% of the float, or 13.35 days of average trading volume. The share count rose 93,501.1% since 2014.
Related: ATOS analyst forecast, ATOS key metrics. See the ATOS stock overview for the latest quote and news.
ATOS ownership FAQ
Who owns the most Atossa Therapeutics stock?
The largest shareholders of Atossa Therapeutics are Vanguard Capital Management, LLC (3.62%), Ameriprise Financial Inc (2.59%), BlackRock Inc (1.65%), Renaissance Technologies Corp (1.32%), Geode Capital Management, LLC (0.93%).
What percentage of Atossa Therapeutics is owned by institutions?
Institutions hold 13.6% of Atossa Therapeutics's shares outstanding; insiders hold 1.85%.
Which funds own Atossa Therapeutics?
The largest fund holders of Atossa Therapeutics are Vanguard MStar Total Stk Mkt Idx Invest (2.57%), Columbia Small Cap Value Discv A (1.93%), Fidelity Extended Market Index (0.45%), Abante Quant Value FI (0.40%), Columbia VP Small Cap Value Discovery 1 (0.34%).
What is Atossa Therapeutics's short interest?
788K shares of Atossa Therapeutics were sold short, 7.90% of the float; at the average daily volume it would take 13.35 days to cover.
Are insiders buying or selling Atossa Therapeutics?
Of the latest 1 reported insider transactions in Atossa Therapeutics (since May 21, 2025), 1 were purchases and 0 were sales.
How many shares of Atossa Therapeutics are outstanding?
Atossa Therapeutics has 10.0M shares outstanding, of which 9.9M are in the public float.