Who owns OneStream, Inc. Class A Common Stock (OS)
Which tracked institutional funds hold OS, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See OS company fundamentals →
Ownership as of the 2026-Q1 13F filings (latest filed 2026-06-15). 13F is disclosed up to 45 days after quarter-end, so the most recent quarter fills in over the following weeks.
Conviction spread
OS’s largest tracked holder by dollar value, GLAZER CAPITAL, LLC, sizes it at 4.0% of its own reported 13F book, while the median holder sizes it at 0.1% of theirs — a 3.9pp conviction gap — its largest holder concentrates the name more heavily than the typical one.
Book-share is each fund’s reported value in OS 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 2025-Q4 and 2026-Q1, we do not read how tracked institutions changed their OS positions: many holders could not be matched across the two filings, most often because the security’s identifier changed and our mapping is incomplete, or because funds are still filing for the newer quarter. 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
Institutional holders
One row per tracked fund, largest reported value first. “% of value” is the fund’s share of this security’s tracked institutional value — not of shares outstanding. Rows marked stale are from an earlier filing than the security’s latest quarter — that fund is absent from the newest snapshot (position exited, or reported under a different name).
| Fund | Shares | Reported value | % of value | Quarter |
|---|---|---|---|---|
| GLAZER CAPITAL, LLC new | 7,537,536 | $181M | 5.9% | 2026-Q1 |
| NORGES BANK added | 6,239,761 | $133M | 4.3% | 2026-Q1 |
| VANGUARD PORTFOLIO MANAGEMENT LLC new | 4,900,450 | $118M | 3.8% | 2026-Q1 |
| Temasek Holdings (Private) Ltd | 4,266,714 | $102M | 3.3% | 2026-Q1 |
| FIL Ltd new | 3,992,145 | $96M | 3.1% | 2026-Q1 |
| VANGUARD CAPITAL MANAGEMENT LLC new | 3,882,231 | $93M | 3.0% | 2026-Q1 |
| AQR Arbitrage LLC new | 3,393,367 | $81M | 2.6% | 2026-Q1 |
| NEXPOINT ASSET MANAGEMENT, L.P. new | 3,358,217 | $81M | 2.6% | 2026-Q1 |
| O'Connor Alternative Investments LLC new | 3,186,804 | $76M | 2.5% | 2026-Q1 |
| Polar Asset Management Partners Inc. new | 2,944,378 | $71M | 2.3% | 2026-Q1 |
| MILLENNIUM MANAGEMENT LLC added | 2,471,107 | $59M | 1.9% | 2026-Q1 |
| BlackRock, Inc. added | 2,339,550 | $56M | 1.8% | 2026-Q1 |
| UBS Group AG added | 2,257,069 | $54M | 1.8% | 2026-Q1 |
| Man Group plc added | 2,204,520 | $53M | 1.7% | 2026-Q1 |
| GOLDMAN SACHS GROUP INC added | 1,985,820 | $48M | 1.5% | 2026-Q1 |
| CITADEL ADVISORS LLC trimmed | 1,890,118 | $45M | 1.5% | 2026-Q1 |
| Pentwater Capital Management LP new | 1,890,000 | $45M | 1.5% | 2026-Q1 |
| First Trust Capital Management L.P. new | 1,842,189 | $44M | 1.4% | 2026-Q1 |
| SOROS FUND MANAGEMENT LLC added | 1,830,222 | $44M | 1.4% | 2026-Q1 |
| TIG Advisors, LLC new | 1,738,231 | $42M | 1.4% | 2026-Q1 |
| MORGAN STANLEY added | 1,651,031 | $40M | 1.3% | 2026-Q1 |
| HSBC HOLDINGS PLC added | 1,595,839 | $38M | 1.2% | 2026-Q1 |
| JPMORGAN CHASE & CO added | 1,467,884 | $35M | 1.1% | 2026-Q1 |
| ODDO BHF ASSET MANAGEMENT SAS new | 1,450,000 | $35M | 1.1% | 2026-Q1 |
| HEALTHCARE OF ONTARIO PENSION PLAN TRUST FUND added | 1,234,961 | $30M | 1.0% | 2026-Q1 |
| ALLIANCEBERNSTEIN L.P. trimmed | 1,535,061 | $28M | 0.9% | 2026-Q1 |
| Qube Research & Technologies Ltd added | 1,133,221 | $27M | 0.9% | 2026-Q1 |
| CITIGROUP INC added | 1,103,394 | $26M | 0.9% | 2026-Q1 |
| GEODE CAPITAL MANAGEMENT, LLC added | 1,099,122 | $26M | 0.9% | 2026-Q1 |
| Capula Management Ltd new | 1,074,711 | $26M | 0.8% | 2026-Q1 |
| MARSHALL WACE, LLP trimmed | 988,636 | $24M | 0.8% | 2026-Q1 |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP added | 984,652 | $24M | 0.8% | 2026-Q1 |
| ALPINE ASSOCIATES MANAGEMENT INC. new | 920,692 | $22M | 0.7% | 2026-Q1 |
| Verition Fund Management LLC added | 862,413 | $21M | 0.7% | 2026-Q1 |
| METEORA CAPITAL, LLC new | 861,800 | $21M | 0.7% | 2026-Q1 |
| BALYASNY ASSET MANAGEMENT L.P. added | 817,569 | $20M | 0.6% | 2026-Q1 |
| SYQUANT CAPITAL SAS new | 789,449 | $19M | 0.6% | 2026-Q1 |
| Nearwater Capital Markets, Ltd new | 707,800 | $17M | 0.6% | 2026-Q1 |
| Fort Baker Capital Management LP new | 689,587 | $17M | 0.5% | 2026-Q1 |
| Westchester Capital Management, LLC new | 677,498 | $16M | 0.5% | 2026-Q1 |
| Grantham, Mayo, Van Otterloo & Co. LLC new | 676,553 | $16M | 0.5% | 2026-Q1 |
| Alberta Investment Management Corp added | 674,500 | $16M | 0.5% | 2026-Q1 |
| BANK OF AMERICA CORP /DE/ added | 623,975 | $15M | 0.5% | 2026-Q1 |
| STATE STREET CORP trimmed | 600,024 | $14M | 0.5% | 2026-Q1 |
| GABELLI FUNDS LLC new | 523,583 | $13M | 0.4% | 2026-Q1 |
| CIBRA Capital Ltd new | 519,691 | $12M | 0.4% | 2026-Q1 |
| Squarepoint Ops LLC added | 518,231 | $12M | 0.4% | 2026-Q1 |
| VANGUARD FIDUCIARY TRUST CO new | 511,124 | $12M | 0.4% | 2026-Q1 |
| Groupe la Francaise new | 509,500 | $12M | 0.4% | 2026-Q1 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC added | 499,512 | $12M | 0.4% | 2026-Q1 |
| GABELLI & Co INVESTMENT ADVISERS, INC. new | 408,372 | $10M | 0.3% | 2026-Q1 |
| BOOTHBAY FUND MANAGEMENT, LLC added | 396,426 | $10M | 0.3% | 2026-Q1 |
| Carmignac Gestion new | 384,893 | $9M | 0.3% | 2026-Q1 |
| CREDIT INDUSTRIEL ET COMMERCIAL new | 365,500 | $9M | 0.3% | 2026-Q1 |
| Taconic Capital Advisors LP new | 341,528 | $8M | 0.3% | 2026-Q1 |
| TPG GP A, LLC new | 325,000 | $8M | 0.3% | 2026-Q1 |
| FIFTH LANE CAPITAL, LP new | 322,630 | $8M | 0.3% | 2026-Q1 |
| AQR CAPITAL MANAGEMENT LLC added | 313,565 | $8M | 0.2% | 2026-Q1 |
| TOKIO MARINE ASSET MANAGEMENT CO LTD new | 284,300 | $7M | 0.2% | 2026-Q1 |
| PICTON MAHONEY ASSET MANAGEMENT added | 274,000 | $7M | 0.2% | 2026-Q1 |
| Trium Capital LLP new | 272,803 | $7M | 0.2% | 2026-Q1 |
| Absolute Gestao de Investimentos Ltda. new | 245,160 | $6M | 0.2% | 2026-Q1 |
| NORTHERN TRUST CORP added | 240,517 | $6M | 0.2% | 2026-Q1 |
| Annis Gardner Whiting Capital Advisors, LLC added | 227,217 | $5M | 0.2% | 2026-Q1 |
| SG Americas Securities, LLC trimmed | 218,311 | $5M | 0.2% | 2026-Q1 |
| New York Life Investment Management LLC new | 215,678 | $5M | 0.2% | 2026-Q1 |
| VANGUARD GROUP INC trimmed | 8,580,460 | $158M | 5.1% | 2025-Q4 stale (1 quarter behind) |
| DARLINGTON PARTNERS CAPITAL MANAGEMENT, LP | 3,839,405 | $71M | 2.3% | 2025-Q4 stale (1 quarter behind) |
| T. Rowe Price Investment Management, Inc. trimmed | 3,839,359 | $71M | 2.3% | 2025-Q4 stale (1 quarter behind) |
| BROWN ADVISORY INC trimmed | 3,376,401 | $62M | 2.0% | 2025-Q4 stale (1 quarter behind) |
| TimesSquare Capital Management, LLC added | 2,668,307 | $49M | 1.6% | 2025-Q4 stale (1 quarter behind) |
| FULLER & THALER ASSET MANAGEMENT, INC. new | 2,592,382 | $48M | 1.5% | 2025-Q4 stale (1 quarter behind) |
| Champlain Investment Partners, LLC trimmed | 2,116,556 | $39M | 1.3% | 2025-Q4 stale (1 quarter behind) |
| WELLINGTON MANAGEMENT GROUP LLP added | 1,342,754 | $25M | 0.8% | 2025-Q4 stale (1 quarter behind) |
| WASATCH ADVISORS LP added | 1,334,873 | $25M | 0.8% | 2025-Q4 stale (1 quarter behind) |
| NEUBERGER BERMAN GROUP LLC trimmed | 1,281,694 | $24M | 0.8% | 2025-Q4 stale (1 quarter behind) |
| AMERICAN CENTURY COMPANIES INC added | 1,271,265 | $23M | 0.8% | 2025-Q4 stale (1 quarter behind) |
| MOORE CAPITAL MANAGEMENT, LP added | 1,204,698 | $22M | 0.7% | 2025-Q4 stale (1 quarter behind) |
| MASSACHUSETTS FINANCIAL SERVICES CO /MA/ trimmed | 1,050,802 | $19M | 0.6% | 2025-Q4 stale (1 quarter behind) |
| FEDERATED HERMES, INC. | 850,000 | $16M | 0.5% | 2025-Q4 stale (1 quarter behind) |
| Clearbridge Investments, LLC added | 613,505 | $11M | 0.4% | 2025-Q4 stale (1 quarter behind) |
| Tensile Capital Management LP new | 541,070 | $10M | 0.3% | 2025-Q4 stale (1 quarter behind) |
| Alyeska Investment Group, L.P. added | 530,341 | $10M | 0.3% | 2025-Q4 stale (1 quarter behind) |
| ALKEON CAPITAL MANAGEMENT LLC trimmed | 475,000 | $9M | 0.3% | 2025-Q4 stale (1 quarter behind) |
| TD Asset Management Inc trimmed | 438,496 | $8M | 0.3% | 2025-Q4 stale (1 quarter behind) |
| Capricorn Fund Managers Ltd new | 380,000 | $7M | 0.2% | 2025-Q4 stale (1 quarter behind) |
| VOLORIDGE INVESTMENT MANAGEMENT, LLC trimmed | 353,662 | $7M | 0.2% | 2025-Q4 stale (1 quarter behind) |
| ARMISTICE CAPITAL, LLC added | 336,000 | $6M | 0.2% | 2025-Q4 stale (1 quarter behind) |
| M&T Bank Corp trimmed | 34,160 | $6M | 0.2% | 2025-Q4 stale (1 quarter behind) |
| EVERGREEN CAPITAL MANAGEMENT LLC trimmed | 325,113 | $6M | 0.2% | 2025-Q4 stale (1 quarter behind) |
| SEI INVESTMENTS CO trimmed | 301,913 | $6M | 0.2% | 2025-Q4 stale (1 quarter behind) |
| KING LUTHER CAPITAL MANAGEMENT CORP added | 268,054 | $5M | 0.2% | 2025-Q4 stale (1 quarter behind) |
| Burkehill Global Management, LP trimmed | 400,000 | $7M | 0.2% | 2025-Q3 stale (2 quarters behind) |
| D. E. Shaw & Co., Inc. added | 371,251 | $11M | 0.3% | 2025-Q2 stale (3 quarters behind) |
| JACOBS LEVY EQUITY MANAGEMENT, INC trimmed | 366,734 | $10M | 0.3% | 2025-Q2 stale (3 quarters behind) |
| Ghisallo Capital Management LLC new | 300,000 | $8M | 0.3% | 2025-Q2 stale (3 quarters behind) |
| Voya Investment Management LLC new | 258,834 | $7M | 0.2% | 2025-Q2 stale (3 quarters behind) |
| Centiva Capital, LP new | 204,950 | $6M | 0.2% | 2025-Q2 stale (3 quarters behind) |
| Fortress Investment Group LLC added | 198,846 | $6M | 0.2% | 2025-Q2 stale (3 quarters behind) |
| CAPSTONE INVESTMENT ADVISORS, LLC new | 175,000 | $5M | 0.2% | 2025-Q2 stale (3 quarters behind) |
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.