OmniAb, Inc. (OABI) Ownership
OABI ownership summary
as of October 18, 2026- Institutions
- 52.8% of shares outstanding
- Insiders
- 15.28% of shares outstanding
- Shares outstanding
- 145.4M
- Float
- 118.2M shares available to trade
- Short interest
- 6.19% 8.2M shares short
- Days to cover
- 5.60 short interest up 15.0% vs prior month
- Institutions 52.80%
- Insiders 15.28%
- Other investors 31.92%
OABI top institutional holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | Whitefort Capital Management, LP. | 7.05% | 10.2M | $47.0M | −4.0M (−27.9%) | June 30, 2026 |
| 2 | BlackRock Inc | 6.12% | 8.9M | $40.8M | +790,609 (+9.8%) | June 30, 2026 |
| 3 | Nomura Holdings Inc | 3.46% | 5.0M | $23.1M | +4.3M (+613.2%) | June 30, 2026 |
| 4 | Cadian Capital Management LP | 2.90% | 4.2M | $19.3M | +54,692 (+1.3%) | June 30, 2026 |
| 5 | Vanguard Capital Management, LLC | 2.65% | 3.9M | $17.7M | −141,296 (−3.5%) | June 30, 2026 |
| 6 | Geode Capital Management, LLC | 1.98% | 2.9M | $13.2M | −41,601 (−1.4%) | June 30, 2026 |
| 7 | Rice Hall James & Associates, LLC | 1.80% | 2.6M | $12.0M | +63,179 (+2.5%) | June 30, 2026 |
| 8 | Private Management Group Inc | 1.61% | 2.3M | $10.8M | −84,396 (−3.5%) | June 30, 2026 |
| 9 | State Street Corp | 1.47% | 2.1M | $9.8M | +66,406 (+3.2%) | June 30, 2026 |
| 10 | Dimensional Fund Advisors, Inc. | 0.87% | 1.3M | $5.8M | −483,149 (−27.7%) | June 30, 2026 |
| 11 | Towerview LLC | 0.81% | 1.2M | $5.4M | +180,000 (+18.0%) | June 30, 2026 |
| 12 | Vanguard Portfolio Management, LLC | 0.67% | 980K | $4.5M | +76,617 (+8.5%) | June 30, 2026 |
| 13 | Charles Schwab Investment Management Inc | 0.67% | 967K | $4.4M | +7,304 (+0.8%) | June 30, 2026 |
| 14 | Northern Trust Corp | 0.65% | 948K | $4.4M | +67,399 (+7.7%) | June 30, 2026 |
| 15 | ADAR1 Capital Management LLC | 0.65% | 947K | $4.3M | +242,222 (+34.3%) | June 30, 2026 |
| 16 | ISTHMUS Partners LLC | 0.55% | 803K | $3.7M | +46,754 (+6.2%) | June 30, 2026 |
| 17 | Vanguard Fiduciary Trust Co | 0.52% | 758K | $3.5M | +32,852 (+4.5%) | June 30, 2026 |
| 18 | Two Sigma Investments LLC | 0.45% | 657K | $3.0M | +144,691 (+28.2%) | June 30, 2026 |
| 19 | Nuveen, LLC | 0.44% | 643K | $3.0M | +18,935 (+3.0%) | June 30, 2026 |
| 20 | Renaissance Technologies Corp | 0.41% | 600K | $2.8M | +330,750 (+122.7%) | June 30, 2026 |
Value at the latest close. Change = shares bought or sold in the latest quarterly filing (13F). In the top 20, 15 holders added 6.4M shares and 5 cut 4.7M.
OABI top mutual fund and ETF holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | iShares Russell 2000 ETF | 1.97% | 2.9M | $13.1M | −32,960 (−1.1%) | September 30, 2026 |
| 2 | Vanguard MStar Total Stk Mkt Idx Invest | 1.64% | 2.4M | $10.9M | — | August 31, 2026 |
| 3 | Fidelity Small Cap Index | 0.82% | 1.2M | $5.5M | +3,271 (+0.3%) | July 31, 2026 |
| 4 | iShares Russell 2000 Value ETF | 0.71% | 1.0M | $4.7M | +1,556 (+0.2%) | September 30, 2026 |
| 5 | iShares Biotechnology ETF | 0.64% | 937K | $4.3M | −7,096 (−0.8%) | September 30, 2026 |
| 6 | Vanguard Russell 2000 ETF | 0.44% | 639K | $2.9M | +6,372 (+1.0%) | September 30, 2026 |
| 7 | Schwab US Small-Cap ETF™ | 0.41% | 599K | $2.7M | +396 (+0.1%) | September 30, 2026 |
| 8 | Fidelity Extended Market Index | 0.41% | 597K | $2.7M | +1,891 (+0.3%) | August 31, 2026 |
| 9 | CREF Total Global Stock Account R3 | 0.26% | 382K | $1.8M | −54,681 (−12.5%) | August 31, 2026 |
| 10 | iShares Micro-Cap ETF | 0.24% | 347K | $1.6M | −2,391 (−0.7%) | September 30, 2026 |
| 11 | DFA US Small Cap I | 0.19% | 271K | $1.2M | −24,411 (−8.3%) | August 31, 2026 |
| 12 | Schwab Small Cap Index | 0.18% | 266K | $1.2M | — | August 31, 2026 |
| 13 | Canada Life US Small-Mid Cap Growth F | 0.18% | 263K | $1.2M | — | July 31, 2026 |
| 14 | Vanguard Health Care ETF | 0.17% | 242K | $1.1M | +263 (+0.1%) | September 30, 2026 |
| 15 | Fidelity Total Market Index | 0.16% | 233K | $1.1M | +26,499 (+12.9%) | August 31, 2026 |
| 16 | Fidelity Enhanced Small Cap Core ETF | 0.15% | 223K | $1.0M | +468 (+0.2%) | September 30, 2026 |
| 17 | iShares Russell 2000 Small-Cap Idx Instl | 0.15% | 212K | $970,904 | — | August 31, 2026 |
| 18 | iShares Core S&P Total US Stock Mkt ETF | 0.14% | 197K | $902,821 | +170 (+0.1%) | September 30, 2026 |
| 19 | Fidelity Series Total Market Index | 0.13% | 186K | $852,244 | +3,301 (+1.8%) | August 31, 2026 |
| 20 | Stt Strt SPDR® Russell2000 US SmCapETF | 0.13% | 184K | $845,841 | −12,837 (−6.5%) | September 30, 2026 |
Funds report holdings monthly or quarterly; dates differ by fund.
OABI insider transactions
latest 16| Date | Name | Transaction | Price | Shares | Value |
|---|---|---|---|---|---|
| 2026-04-07 | Charles S Berkman | Sell | $1.49 | 7,157 | $10,664 |
| 2026-04-07 | Kurt A Gustafson | Sell | $1.49 | 6,913 | $10,300 |
| 2026-04-07 | Matthew W Foehr | Sell | $1.49 | 19,244 | $28,674 |
| 2026-02-18 | Charles S Berkman | Sell | $1.71 | 9,673 | $16,541 |
| 2026-02-18 | Kurt A Gustafson | Sell | $1.71 | 9,301 | $15,905 |
| 2026-02-18 | Matthew W Foehr | Sell | $1.71 | 30,843 | $52,742 |
| 2026-02-17 | Charles S Berkman | Sell | $1.70 | 6,990 | $11,883 |
| 2026-02-17 | Kurt A Gustafson | Sell | $1.70 | 6,828 | $11,608 |
| 2026-02-17 | Matthew W Foehr | Sell | $1.70 | 20,754 | $35,282 |
| 2025-12-08 | Charles S Berkman | Sell | $1.96 | 8,044 | $15,766 |
| 2025-12-08 | Kurt A Gustafson | Sell | $1.96 | 23,922 | $46,887 |
| 2025-12-08 | Matthew W Foehr | Sell | $1.96 | 13,666 | $26,785 |
| 2025-11-07 | John L Higgins | Buy | $1.38 | 41,038 | $56,632 |
| 2025-11-06 | John L Higgins | Buy | $1.41 | 36,223 | $51,074 |
| 2025-05-14 | Steven Love | Buy | $1.46 | 25,000 | $36,500 |
| 2025-05-12 | John L Higgins | Buy | $1.44 | 65,000 | $93,600 |
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.
OABI shares outstanding
Year-end shares outstanding, adjusted for splits.
Who owns OABI
Institutional investors own 52.8% of OmniAb's shares and insiders 15.28%. The largest holder is Whitefort Capital Management, LP. with 7.05% of the shares (10.2M), as of June 30, 2026. Among the top 20 institutions, 15 added shares and 5 reduced their stake in the latest filings. Short interest is 6.19% of the float, or 5.60 days of average trading volume. The share count rose 11.3% since 2020.
Related: OABI analyst forecast, OABI key metrics. See the OABI stock overview for the latest quote and news.
OABI ownership FAQ
Who owns the most OmniAb stock?
The largest shareholders of OmniAb are Whitefort Capital Management, LP. (7.05%), BlackRock Inc (6.12%), Nomura Holdings Inc (3.46%), Cadian Capital Management LP (2.90%), Vanguard Capital Management, LLC (2.65%).
What percentage of OmniAb is owned by institutions?
Institutions hold 52.8% of OmniAb's shares outstanding; insiders hold 15.28%.
Which funds own OmniAb?
The largest fund holders of OmniAb are iShares Russell 2000 ETF (1.97%), Vanguard MStar Total Stk Mkt Idx Invest (1.64%), Fidelity Small Cap Index (0.82%), iShares Russell 2000 Value ETF (0.71%), iShares Biotechnology ETF (0.64%).
What is OmniAb's short interest?
8.2M shares of OmniAb were sold short, 6.19% of the float; at the average daily volume it would take 5.60 days to cover.
Are insiders buying or selling OmniAb?
Of the latest 16 reported insider transactions in OmniAb (since May 12, 2025), 4 were purchases and 12 were sales.
How many shares of OmniAb are outstanding?
OmniAb has 145.4M shares outstanding, of which 118.2M are in the public float.