Who owns Magnite (MGNI)
Which tracked institutional funds hold MGNI, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See MGNI 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 MGNI is one-sided between 2026-Q1 and 2026-Q2: 148 added or opened and 30 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
MGNI’s largest tracked holder by dollar value, BlackRock, Inc., sizes it at 0.0% of its own reported 13F book, while the median holder sizes it at 0.0% of theirs — a 0.0pp gap the other way — the median holder sizes MGNI more heavily than its largest holder by dollar value does.
Book-share is each fund’s reported value in MGNI 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 296 tracked filers holding MGNI, 169 increased or opened the position and 141 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 MGNI 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 22
- AMERIPRISE FINANCIAL INC$12M
- BANK OF MONTREAL /CAN/$10M
- EVR Research LP$9M
- Jump Financial, LLC$8M
- Trexquant Investment LP$6M
- Alyeska Investment Group, L.P.$6M
Full exits 15
- No Street GP LP$19M
- Capital World Investors$5M
- HARBOR CAPITAL ADVISORS, INC.$4M
- NORGES BANK$3M
- WEDGE CAPITAL MANAGEMENT L L P/NC$2M
- Walleye Trading LLC$2M
Largest adds
- BlackRock, Inc.$103M
- FMR LLC$94M
- VANGUARD PORTFOLIO MANAGEMENT LLC$64M
- CANADA PENSION PLAN INVESTMENT BOARD$56M
- DIMENSIONAL FUND ADVISORS LP$53M
- VANGUARD CAPITAL MANAGEMENT LLC$45M
Largest trims
- Schonfeld Strategic Advisors LLC$8M
- Man Group plc$7M
- BALYASNY ASSET MANAGEMENT L.P.$5M
- CenterBook Partners LP$4M
- TWO SIGMA INVESTMENTS, LP$4M
- CITADEL ADVISORS LLC$4M
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 |
|---|---|---|---|---|
| BlackRock, Inc. added | 12,713,156 | $241M | 9.3% | 2026-Q2 |
| VANGUARD PORTFOLIO MANAGEMENT LLC added | 8,197,286 | $156M | 6.0% | 2026-Q2 |
| FMR LLC added | 7,759,426 | $147M | 5.7% | 2026-Q2 |
| VANGUARD CAPITAL MANAGEMENT LLC added | 6,225,195 | $118M | 4.6% | 2026-Q2 |
| WELLINGTON MANAGEMENT GROUP LLP trimmed | 6,044,492 | $115M | 4.4% | 2026-Q2 |
| DIMENSIONAL FUND ADVISORS LP added | 5,260,132 | $100M | 3.9% | 2026-Q2 |
| Boston Partners added | 5,013,835 | $96M | 3.7% | 2026-Q2 |
| AMERICAN CENTURY COMPANIES INC trimmed | 4,622,736 | $88M | 3.4% | 2026-Q2 |
| Capital Research Global Investors trimmed | 3,869,159 | $73M | 2.8% | 2026-Q2 |
| Nuveen, LLC added | 3,794,811 | $72M | 2.8% | 2026-Q2 |
| GEODE CAPITAL MANAGEMENT, LLC added | 3,789,959 | $72M | 2.8% | 2026-Q2 |
| Edenbrook Capital, LLC added | 3,555,615 | $67M | 2.6% | 2026-Q2 |
| STATE STREET CORP added | 3,528,075 | $67M | 2.6% | 2026-Q2 |
| 325 CAPITAL LLC added | 3,412,694 | $65M | 2.5% | 2026-Q2 |
| Nine Ten Capital Management LLC trimmed | 3,261,283 | $62M | 2.4% | 2026-Q2 |
| Granahan Investment Management, LLC added | 3,083,211 | $59M | 2.3% | 2026-Q2 |
| CANADA PENSION PLAN INVESTMENT BOARD added | 2,995,093 | $57M | 2.2% | 2026-Q2 |
| JANE STREET GROUP, LLC added | 2,199,191 | $42M | 1.6% | 2026-Q2 |
| Park West Asset Management LLC added | 2,000,000 | $38M | 1.5% | 2026-Q2 |
| MORGAN STANLEY added | 1,991,732 | $38M | 1.5% | 2026-Q2 |
| Qube Research & Technologies Ltd added | 1,955,989 | $37M | 1.4% | 2026-Q2 |
| Blue Grotto Capital, LLC added | 1,706,741 | $32M | 1.3% | 2026-Q2 |
| KENNEDY CAPITAL MANAGEMENT LLC trimmed | 1,666,799 | $32M | 1.2% | 2026-Q2 |
| NORTHERN TRUST CORP added | 1,553,412 | $29M | 1.1% | 2026-Q2 |
| ROYCE & ASSOCIATES LP added | 1,473,397 | $28M | 1.1% | 2026-Q2 |
| GOLDMAN SACHS GROUP INC trimmed | 1,466,640 | $28M | 1.1% | 2026-Q2 |
| Ophir Asset Management Pty Ltd trimmed | 1,450,061 | $28M | 1.1% | 2026-Q2 |
| VICTORY CAPITAL MANAGEMENT INC trimmed | 1,235,384 | $23M | 0.9% | 2026-Q2 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC added | 1,203,189 | $23M | 0.9% | 2026-Q2 |
| BANK OF AMERICA CORP /DE/ added | 1,181,832 | $22M | 0.9% | 2026-Q2 |
| GRIZZLYROCK CAPITAL, LLC trimmed | 1,164,628 | $22M | 0.9% | 2026-Q2 |
| Bank of New York Mellon Corp added | 1,162,198 | $22M | 0.9% | 2026-Q2 |
| Maestria Partners LLC trimmed | 1,158,430 | $22M | 0.9% | 2026-Q2 |
| Meros Investment Management, LP trimmed | 991,335 | $19M | 0.7% | 2026-Q2 |
| VANGUARD FIDUCIARY TRUST CO trimmed | 989,092 | $19M | 0.7% | 2026-Q2 |
| MILLENNIUM MANAGEMENT LLC trimmed | 764,819 | $15M | 0.6% | 2026-Q2 |
| QVT Financial LP added | 747,437 | $14M | 0.5% | 2026-Q2 |
| UBS Group AG added | 746,350 | $14M | 0.5% | 2026-Q2 |
| OBERWEIS ASSET MANAGEMENT INC/ added | 735,000 | $14M | 0.5% | 2026-Q2 |
| SILVERCREST ASSET MANAGEMENT GROUP LLC added | 707,749 | $13M | 0.5% | 2026-Q2 |
| PICTON MAHONEY ASSET MANAGEMENT added | 691,471 | $13M | 0.5% | 2026-Q2 |
| Kopion Asset Management, LLC trimmed | 674,451 | $13M | 0.5% | 2026-Q2 |
| First Eagle Investment Management, LLC added | 670,788 | $13M | 0.5% | 2026-Q2 |
| BALYASNY ASSET MANAGEMENT L.P. trimmed | 666,554 | $13M | 0.5% | 2026-Q2 |
| AMERIPRISE FINANCIAL INC added | 619,573 | $12M | 0.5% | 2026-Q2 |
| S SQUARED TECHNOLOGY, LLC added | 567,862 | $11M | 0.4% | 2026-Q2 |
| Schonfeld Strategic Advisors LLC trimmed | 562,195 | $11M | 0.4% | 2026-Q2 |
| NOMURA ASSET MANAGEMENT CO LTD trimmed | 553,900 | $11M | 0.4% | 2026-Q2 |
| BANK OF MONTREAL /CAN/ added | 533,757 | $10M | 0.4% | 2026-Q2 |
| KING LUTHER CAPITAL MANAGEMENT CORP trimmed | 503,581 | $10M | 0.4% | 2026-Q2 |
| PRINCIPAL FINANCIAL GROUP INC added | 497,522 | $9M | 0.4% | 2026-Q2 |
| EVR Research LP new | 480,000 | $9M | 0.4% | 2026-Q2 |
| CITADEL ADVISORS LLC trimmed | 472,865 | $9M | 0.3% | 2026-Q2 |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP added | 461,849 | $9M | 0.3% | 2026-Q2 |
| Manatuck Hill Partners, LLC added | 450,000 | $9M | 0.3% | 2026-Q2 |
| Jump Financial, LLC new | 428,036 | $8M | 0.3% | 2026-Q2 |
| JPMORGAN CHASE & CO trimmed | 407,025 | $8M | 0.3% | 2026-Q2 |
| NORDEA INVESTMENT MANAGEMENT AB trimmed | 386,327 | $7M | 0.3% | 2026-Q2 |
| COMMONWEALTH EQUITY SERVICES, LLC added | 368,199 | $7M | 0.3% | 2026-Q2 |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC added | 364,638 | $7M | 0.3% | 2026-Q2 |
| MARSHALL WACE, LLP added | 341,864 | $6M | 0.3% | 2026-Q2 |
| Trexquant Investment LP new | 333,429 | $6M | 0.2% | 2026-Q2 |
| Alyeska Investment Group, L.P. new | 326,839 | $6M | 0.2% | 2026-Q2 |
| 1492 Capital Management LLC trimmed | 317,750 | $6M | 0.2% | 2026-Q2 |
| RAYMOND JAMES FINANCIAL INC added | 309,931 | $6M | 0.2% | 2026-Q2 |
| Swiss National Bank added | 289,700 | $5M | 0.2% | 2026-Q2 |
| Lisanti Capital Growth, LLC trimmed | 289,030 | $5M | 0.2% | 2026-Q2 |
| RICE HALL JAMES & ASSOCIATES, LLC added | 283,919 | $5M | 0.2% | 2026-Q2 |
| ExodusPoint Capital Management, LP added | 271,869 | $5M | 0.2% | 2026-Q2 |
| Norwood Investment Partners, LP trimmed | 235,000 | $4M | 0.2% | 2026-Q2 |
| BARCLAYS PLC added | 233,693 | $4M | 0.2% | 2026-Q2 |
| Squarepoint Ops LLC trimmed | 230,234 | $4M | 0.2% | 2026-Q2 |
| Senvest Management, LLC | 224,100 | $4M | 0.2% | 2026-Q2 |
| Invesco Ltd. trimmed | 222,213 | $4M | 0.2% | 2026-Q2 |
| Hilton Capital Management, LLC added | 219,406 | $4M | 0.2% | 2026-Q2 |
| Pillsbury Lake Capital LLC trimmed | 217,753 | $4M | 0.2% | 2026-Q2 |
| Cerity Partners LLC added | 200,984 | $4M | 0.1% | 2026-Q2 |
| PRICE T ROWE ASSOCIATES INC /MD/ added | 199,445 | $4M | 0.1% | 2026-Q2 |
| VOYA INVESTMENT MANAGEMENT LLC trimmed | 196,662 | $4M | 0.1% | 2026-Q2 |
| RHUMBLINE ADVISERS added | 195,811 | $4M | 0.1% | 2026-Q2 |
| Occam Crest Management LP new | 195,000 | $4M | 0.1% | 2026-Q2 |
| GREAT LAKES ADVISORS, LLC new | 176,615 | $3M | 0.1% | 2026-Q2 |
| AQR CAPITAL MANAGEMENT LLC added | 176,599 | $3M | 0.1% | 2026-Q2 |
| STATE OF WISCONSIN INVESTMENT BOARD trimmed | 172,277 | $3M | 0.1% | 2026-Q2 |
| CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM trimmed | 172,047 | $3M | 0.1% | 2026-Q2 |
| DEAN INVESTMENT ASSOCIATES, LLC new | 167,927 | $3M | 0.1% | 2026-Q2 |
| Legato Capital Management LLC added | 166,918 | $3M | 0.1% | 2026-Q2 |
| Tidal Investments LLC added | 165,838 | $3M | 0.1% | 2026-Q2 |
| SEI INVESTMENTS CO trimmed | 165,553 | $3M | 0.1% | 2026-Q2 |
| DEUTSCHE BANK AG\ added | 165,040 | $3M | 0.1% | 2026-Q2 |
| LPL Financial LLC added | 163,837 | $3M | 0.1% | 2026-Q2 |
| Quantinno Capital Management LP added | 161,782 | $3M | 0.1% | 2026-Q2 |
| P.A.W. CAPITAL CORP trimmed | 160,000 | $3M | 0.1% | 2026-Q2 |
| CLOUGH CAPITAL PARTNERS L P added | 159,586 | $3M | 0.1% | 2026-Q2 |
| Concentric Capital Strategies, LP trimmed | 146,698 | $3M | 0.1% | 2026-Q2 |
| Caption Management, LLC trimmed | 145,590 | $3M | 0.1% | 2026-Q2 |
| VANGUARD ASSET MANAGEMENT, Ltd added | 140,438 | $3M | 0.1% | 2026-Q2 |
| ALGERT GLOBAL LLC trimmed | 137,505 | $3M | 0.1% | 2026-Q2 |
| WELLS FARGO & COMPANY/MN added | 137,396 | $3M | 0.1% | 2026-Q2 |
| FRANKLIN RESOURCES INC added | 122,336 | $2M | 0.1% | 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.