Who owns OmniAb (OABI)
Which tracked institutional funds hold OABI, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See OABI company fundamentals →
Ownership as of the 2026-Q2 13F filings (latest filed 2026-09-22). 13F is disclosed up to 45 days after quarter-end, so the most recent quarter fills in over the following weeks.
How the tape is positioned
The tracked-fund tape on OABI is one-sided between 2026-Q1 and 2026-Q2: 25 added or opened and 1 trimmed or exited — on balance accumulating.
A prompt to read the filings, not a verdict. 13F is a quarter-end snapshot disclosed up to 45 days late; a fund adds or exits for mandate, benchmark, and timing reasons that have nothing to do with a view on the stock. This is a starting question, not a signal to trade.
Conviction spread
OABI’s largest tracked holder by dollar value, Whitefort Capital Management, LP, sizes it at 6.4% of its own reported 13F book, while the median holder sizes it at 0.0% of theirs — a 6.4pp conviction gap — its largest holder concentrates the name more heavily than the typical one.
Book-share is each fund’s reported value in OABI divided by its whole reported 13F book, so it is comparable across funds of different sizes and is unaffected by stock splits. A higher share means a fund has committed more of its book to the name — a starting question about conviction, not a verdict or a signal to trade.
Institutional & insider positioning
Between 2026-Q1 and 2026-Q2, across 140 tracked filers holding OABI, 73 increased or opened the position and 52 reduced or closed it; over the same quarter, open-market insider Form 4s were net sales.
This fuses two public signals for the same quarter — how tracked institutions changed their positions and whether insiders bought or sold in the open market. It describes what was filed; it is a starting question, not a verdict or a signal to trade.
New buyers & exits
Funds opening or closing a position in OABI between the 2026-Q1 and 2026-Q2 13F filings, and the largest changes among funds holding it in both. New buyers and exits are counted on fund presence (split-invariant); adds and trims are measured on reported value.
New buyers 1
- MACKENZIE FINANCIAL CORP$1M
Largest adds
- NOMURA HOLDINGS INC$11M
- BlackRock, Inc.$9M
- CADIAN CAPITAL MANAGEMENT, LP$4M
- VANGUARD CAPITAL MANAGEMENT LLC$3M
- Whitefort Capital Management, LP$3M
- GEODE CAPITAL MANAGEMENT, LLC$3M
Largest trims
- EverSource Wealth Advisors, LLC$548K
Institutional holders
One row per tracked fund, most shares held first (every row is from one quarter; reported value breaks ties). “% of value” is the fund’s share of this security’s tracked institutional value — not of shares outstanding.
| Fund | Shares | Reported value | % of value | Quarter |
|---|---|---|---|---|
| Whitefort Capital Management, LP trimmed | 10,248,658 | $25M | 17.5% | 2026-Q2 |
| BlackRock, Inc. added | 8,897,490 | $22M | 15.2% | 2026-Q2 |
| NOMURA HOLDINGS INC added | 5,028,160 | $12M | 8.6% | 2026-Q2 |
| CADIAN CAPITAL MANAGEMENT, LP added | 4,211,821 | $10M | 7.2% | 2026-Q2 |
| VANGUARD CAPITAL MANAGEMENT LLC trimmed | 3,852,356 | $9M | 6.6% | 2026-Q2 |
| GEODE CAPITAL MANAGEMENT, LLC trimmed | 2,883,978 | $7M | 4.9% | 2026-Q2 |
| RICE HALL JAMES & ASSOCIATES, LLC added | 2,610,434 | $6M | 4.5% | 2026-Q2 |
| PRIVATE MANAGEMENT GROUP INC trimmed | 2,344,770 | $6M | 4.0% | 2026-Q2 |
| STATE STREET CORP added | 2,133,549 | $5M | 3.6% | 2026-Q2 |
| DIMENSIONAL FUND ADVISORS LP trimmed | 1,262,099 | $3M | 2.2% | 2026-Q2 |
| TOWERVIEW LLC added | 1,180,000 | $3M | 2.0% | 2026-Q2 |
| VANGUARD PORTFOLIO MANAGEMENT LLC added | 980,416 | $2M | 1.7% | 2026-Q2 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC added | 966,877 | $2M | 1.7% | 2026-Q2 |
| NORTHERN TRUST CORP added | 948,294 | $2M | 1.6% | 2026-Q2 |
| ADAR1 Capital Management, LLC added | 947,412 | $2M | 1.6% | 2026-Q2 |
| LMR Partners LLP | 897,392 | $80K | 0.1% | 2026-Q2 |
| ISTHMUS PARTNERS, LLC added | 803,428 | $2M | 1.4% | 2026-Q2 |
| VANGUARD FIDUCIARY TRUST CO added | 758,460 | $2M | 1.3% | 2026-Q2 |
| ARISTEIA CAPITAL, L.L.C. | 679,919 | $54K | 0.0% | 2026-Q2 |
| TWO SIGMA INVESTMENTS, LP added | 657,432 | $2M | 1.1% | 2026-Q2 |
| Nuveen, LLC added | 642,811 | $2M | 1.1% | 2026-Q2 |
| RENAISSANCE TECHNOLOGIES LLC added | 600,350 | $1M | 1.0% | 2026-Q2 |
| D. E. Shaw & Co., Inc. added | 559,404 | $1M | 1.0% | 2026-Q2 |
| MACKENZIE FINANCIAL CORP new | 489,134 | $1M | 0.8% | 2026-Q2 |
| MILLENNIUM MANAGEMENT LLC trimmed | 474,159 | $864K | 0.6% | 2026-Q2 |
| Hudson Bay Capital Management LP | 465,229 | $41K | 0.0% | 2026-Q2 |
| GOLDMAN SACHS GROUP INC trimmed | 384,573 | $946K | 0.7% | 2026-Q2 |
| MORGAN STANLEY trimmed | 371,506 | $914K | 0.6% | 2026-Q2 |
| Bank of New York Mellon Corp added | 318,406 | $783K | 0.5% | 2026-Q2 |
| Sculptor Capital LP | 293,802 | $23K | 0.0% | 2026-Q2 |
| TLS Advisors LLC trimmed | 220,685 | $543K | 0.4% | 2026-Q2 |
| Calamos Advisors LLC | 200,000 | $17K | 0.0% | 2026-Q2 |
| FMR LLC added | 199,818 | $492K | 0.3% | 2026-Q2 |
| BRIDGEWAY CAPITAL MANAGEMENT, LLC | 198,900 | $489K | 0.3% | 2026-Q2 |
| Arbiter Partners Capital Management LLC | 192,585 | $474K | 0.3% | 2026-Q2 |
| RHUMBLINE ADVISERS added | 171,957 | $423K | 0.3% | 2026-Q2 |
| Palumbo Wealth Management LLC added | 161,975 | $398K | 0.3% | 2026-Q2 |
| Invesco Ltd. added | 161,376 | $397K | 0.3% | 2026-Q2 |
| ARROWSTREET CAPITAL, LIMITED PARTNERSHIP new | 159,621 | $393K | 0.3% | 2026-Q2 |
| MMCAP International Inc. SPC | 158,333 | $14K | 0.0% | 2026-Q2 |
| AQR CAPITAL MANAGEMENT LLC added | 157,716 | $388K | 0.3% | 2026-Q2 |
| ALLIANCEBERNSTEIN L.P. added | 155,992 | $245K | 0.2% | 2026-Q2 |
| BANK OF AMERICA CORP /DE/ added | 149,493 | $368K | 0.3% | 2026-Q2 |
| Walleye Capital LLC trimmed | 144,427 | $355K | 0.2% | 2026-Q2 |
| Cornerstone Capital, Inc. | 142,286 | $350K | 0.2% | 2026-Q2 |
| JPMORGAN CHASE & CO trimmed | 107,049 | $275K | 0.2% | 2026-Q2 |
| DEUTSCHE BANK AG\ added | 100,842 | $248K | 0.2% | 2026-Q2 |
| WELLS FARGO & COMPANY/MN added | 100,229 | $247K | 0.2% | 2026-Q2 |
| PRICE T ROWE ASSOCIATES INC /MD/ added | 80,106 | $198K | 0.1% | 2026-Q2 |
| AMERICAN CENTURY COMPANIES INC added | 75,083 | $185K | 0.1% | 2026-Q2 |
| XTX Topco Ltd added | 73,907 | $182K | 0.1% | 2026-Q2 |
| Connor, Clark & Lunn Investment Management Ltd. added | 72,357 | $178K | 0.1% | 2026-Q2 |
| MetLife Investment Management, LLC added | 65,744 | $162K | 0.1% | 2026-Q2 |
| Russell Investments Group, Ltd. added | 63,783 | $157K | 0.1% | 2026-Q2 |
| CITADEL ADVISORS LLC trimmed | 58,190 | $143K | 0.1% | 2026-Q2 |
| CITIGROUP INC added | 54,667 | $134K | 0.1% | 2026-Q2 |
| SEI INVESTMENTS CO trimmed | 53,390 | $131K | 0.1% | 2026-Q2 |
| Shay Capital LLC added | 51,500 | $127K | 0.1% | 2026-Q2 |
| Vanguard Global Advisers, LLC | 51,396 | $126K | 0.1% | 2026-Q2 |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. added | 50,644 | $125K | 0.1% | 2026-Q2 |
| BLAIR WILLIAM & CO/IL added | 43,394 | $107K | 0.1% | 2026-Q2 |
| Police & Firemen's Retirement System of New Jersey added | 42,217 | $104K | 0.1% | 2026-Q2 |
| PRUDENTIAL FINANCIAL INC added | 38,969 | $96K | 0.1% | 2026-Q2 |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP trimmed | 35,691 | $88K | 0.1% | 2026-Q2 |
| Squarepoint Ops LLC added | 35,357 | $87K | 0.1% | 2026-Q2 |
| LPL Financial LLC trimmed | 34,821 | $86K | 0.1% | 2026-Q2 |
| WOODSTOCK CORP trimmed | 29,376 | $72K | 0.1% | 2026-Q2 |
| INTECH INVESTMENT MANAGEMENT LLC trimmed | 27,824 | $68K | 0.0% | 2026-Q2 |
| BARCLAYS PLC trimmed | 26,469 | $65K | 0.0% | 2026-Q2 |
| MANUFACTURERS LIFE INSURANCE COMPANY, THE trimmed | 24,785 | $61K | 0.0% | 2026-Q2 |
| VOYA INVESTMENT MANAGEMENT LLC added | 23,613 | $58K | 0.0% | 2026-Q2 |
| China Universal Asset Management Co., Ltd. trimmed | 23,072 | $57K | 0.0% | 2026-Q2 |
| BFSG, LLC | 20,815 | $51K | 0.0% | 2026-Q2 |
| Qube Research & Technologies Ltd new | 20,186 | $50K | 0.0% | 2026-Q2 |
| BNP PARIBAS FINANCIAL MARKETS trimmed | 19,822 | $49K | 0.0% | 2026-Q2 |
| Quadrature Capital Ltd added | 19,492 | $48K | 0.0% | 2026-Q2 |
| ProShare Advisors LLC trimmed | 19,155 | $47K | 0.0% | 2026-Q2 |
| Thrive Wealth Management, LLC added | 18,046 | $44K | 0.0% | 2026-Q2 |
| UBS Group AG trimmed | 17,849 | $44K | 0.0% | 2026-Q2 |
| TWO SIGMA SECURITIES, LLC new | 15,726 | $39K | 0.0% | 2026-Q2 |
| OSAIC HOLDINGS, INC. added | 15,459 | $38K | 0.0% | 2026-Q2 |
| CANADA PENSION PLAN INVESTMENT BOARD new | 15,100 | $37K | 0.0% | 2026-Q2 |
| VICTORY CAPITAL MANAGEMENT INC added | 13,649 | $34K | 0.0% | 2026-Q2 |
| MERCER GLOBAL ADVISORS INC /ADV added | 12,357 | $30K | 0.0% | 2026-Q2 |
| CHOREO, LLC added | 12,232 | $30K | 0.0% | 2026-Q2 |
| Anson Funds Management LP | 11,833 | $29K | 0.0% | 2026-Q2 |
| NEW YORK STATE COMMON RETIREMENT FUND | 11,806 | $29K | 0.0% | 2026-Q2 |
| Legal & General Group Plc added | 11,284 | $28K | 0.0% | 2026-Q2 |
| Legato Capital Management LLC trimmed | 10,913 | $27K | 0.0% | 2026-Q2 |
| Vanguard Personalized Indexing Management, LLC trimmed | 10,793 | $27K | 0.0% | 2026-Q2 |
| XPONANCE LLC new | 10,472 | $26K | 0.0% | 2026-Q2 |
| Ameritas Investment Partners, Inc. | 9,652 | $24K | 0.0% | 2026-Q2 |
| Tower Research Capital LLC (TRC) trimmed | 8,044 | $20K | 0.0% | 2026-Q2 |
| SUMMIT SECURITIES GROUP LLC new | 7,882 | $19K | 0.0% | 2026-Q2 |
| Steigerwald, Gordon & Koch Inc. | 7,673 | $19K | 0.0% | 2026-Q2 |
| Mirae Asset Global Investments Co., Ltd. trimmed | 6,484 | $16K | 0.0% | 2026-Q2 |
| Integrated Wealth Concepts LLC trimmed | 5,710 | $14K | 0.0% | 2026-Q2 |
| ROYAL BANK OF CANADA added | 5,219 | $13K | 0.0% | 2026-Q2 |
| GF FUND MANAGEMENT CO. LTD. trimmed | 2,973 | $7K | 0.0% | 2026-Q2 |
| Allworth Financial LP added | 2,771 | $7K | 0.0% | 2026-Q2 |
Ownership over time
Tracked institutional holder count and total shares held by filing quarter (independent scales). The curated-era tail and any mid-ingest latest quarter are handled honestly — a partial quarter is not drawn as a collapse.
Reading this table
Funds hold the same stock for different reasons — an index fund “holds” almost everything, an active manager sizes a name to a mandate and a benchmark, and each fund entered at its own price and time. Because 13F is filed up to 45 days after quarter-end, every row is a backward-looking snapshot; a manager may have traded since. Share-class siblings (a company’s A and C shares) are rolled up to one line so a dual-class name is never double-counted. Compare like-for-like. A large holder is not an endorsement, and a fund exiting is not a warning — this is a starting question, not a verdict.
About 13F filings
A Form 13F is a quarterly disclosure that institutional investment managers with over $100 million in US-listed equities must file with the SEC. In plain English: it is a snapshot of the long stock positions a fund held at the end of a quarter. It covers long US-listed equities only — not short positions, options, cash, or private holdings — and the funds shown are the large sample we track, not the complete 13F universe.