Ranked by reported Q1 2026 13F market value
Share of total reported institutional value in MGNI held by the largest 10 / 25 filers.
| # | Institution | Shares Held | Market Value | QoQ Change | Ownership % | % of Fund |
|---|---|---|---|---|---|---|
| 1 | BlackRock, Inc. | 11.7M | $138.5M | +0.5% | 8.140% | 0.00% |
| 2 | WELLINGTON MANAGEMENT GROUP LLP | 9.2M | $109.2M | +6.5% | 6.418% | 0.02% |
| 3 | VANGUARD PORTFOLIO MANAGEMENT LLC | 7.7M | $91.8M | — | 5.395% | 0.00% |
| 4 | VANGUARD CAPITAL MANAGEMENT LLC | 6.2M | $73.5M | — | 4.322% | 0.00% |
| 5 | Capital Research Global Investors | 5.0M | $59.6M | -61.1% | 3.505% | 0.01% |
| 6 | Boston Partners | 4.7M | $56.1M | +14.9% | 3.296% | 0.06% |
| 7 | AMERICAN CENTURY COMPANIES INC | 4.6M | $55.0M | -12.5% | 3.231% | 0.03% |
| 8 | FMR LLC | 4.5M | $53.5M | -32.7% | 3.147% | 0.00% |
| 9 | DIMENSIONAL FUND ADVISORS LP | 4.0M | $47.3M | +10.2% | 2.782% | 0.01% |
| 10 | Nuveen, LLC | 3.6M | $42.6M | +1.7% | 2.507% | 0.01% |
| 11 | GEODE CAPITAL MANAGEMENT, LLC | 3.6M | $42.2M | +3.5% | 2.481% | 0.00% |
| 12 | Nine Ten Capital Management LLC | 3.5M | $41.4M | +15.9% | 2.431% | 13.14% |
| 13 | Edenbrook Capital, LLC | 3.4M | $40.4M | — | 2.373% | 27.64% |
| 14 | STATE STREET CORP | 3.2M | $37.6M | +0.7% | 2.209% | 0.00% |
| 15 | GRANAHAN INVESTMENT MANAGEMENT INC/MA | 2.6M | $30.3M | -18.1% | 1.783% | 1.47% |
| 16 | CITADEL ADVISORS LLC | 2.2M | $26.1M | — | 1.534% | 0.01% |
| 17 | Ophir Asset Management Pty Ltd | 2.1M | $25.2M | -11.2% | 1.479% | 2.93% |
| 18 | 325 CAPITAL LLC | 2.0M | $23.8M | 0.0% | 1.400% | 8.68% |
| 19 | Caption Management, LLC | 1.9M | $22.6M | — | 1.330% | 0.22% |
| 20 | KENNEDY CAPITAL MANAGEMENT, INC. | 1.8M | $20.8M | +22.1% | 1.224% | 0.44% |
| 21 | No Street GP LP | 1.6M | $19.3M | +10.4% | 1.137% | 1.29% |
| 22 | Schonfeld Strategic Advisors LLC | 1.6M | $19.1M | +105.9% | 1.121% | 0.14% |
| 23 | GOLDMAN SACHS GROUP INC | 1.5M | $17.8M | -14.8% | 1.048% | 0.00% |
| 24 | BALYASNY ASSET MANAGEMENT LLC | 1.5M | $17.8M | +71.8% | 1.048% | 0.06% |
| 25 | Squarepoint Ops LLC | 1.4M | $16.5M | -21.4% | 0.971% | 0.02% |
denotes a marquee investor (Buffett, Burry, ARK, Tiger Global, Pershing Square, Baupost and other widely-followed managers). “% of Fund” shows how much of that investor’s total 13F portfolio is invested in MGNI — a direct measure of their conviction.
Filings activity in MGNI during Q1 2026, grouped by how each filer changed its position.
8 quarters of 13F filings · Δ columns show change vs prior quarter
| Quarter | Inst. Holders | Δ Holders | Ownership % | Δ Ownership | Total 13F Value | Δ Value |
|---|---|---|---|---|---|---|
| Q1 2026 | 291 | 2.7% | 68.37% | 26.28 pp | $1.59B | 28% |
| Q4 2025 | 299 | 1.6% | 94.65% | 33.85 pp | $2.20B | 26% |
| Q3 2025 | 304 | +8.6% | 128.50% | 25.68 pp | $2.99B | 17% |
| Q2 2025 | 280 | 1.1% | 154.18% | +88.04 pp | $3.59B | +133% |
| Q1 2025 | 283 | +3.3% | 66.14% | 17.03 pp | $1.54B | 20% |
| Q4 2024 | 274 | +2.2% | 83.17% | +11.97 pp | $1.94B | +17% |
| Q3 2024 | 268 | +2.7% | 71.20% | +14.78 pp | $1.66B | +26% |
| Q2 2024 | 261 | — | 56.42% | — | $1.31B | — |
Source: SEC 13F institutional filings. Ownership % requires market cap data and will show once linked. Δ columns compare to the immediately prior filed quarter.
Quick answers to the most common questions about buying MGNI stock.
Based on Q1 2026 13F filings, institutional ownership of Magnite, Inc. stands at 68.4%, held across 291 reporting institutions.
BlackRock, Inc. is the largest reported institutional holder of MGNI, with approximately 11,657,496 shares worth $0.14B as of Q1 2026.
Yes — 1 widely-followed marquee investor appear among the top 25 institutional holders of MGNI, including CITADEL ADVISORS LLC.
Our composite Smart Money Score for MGNI is 34 out of 100 (Bearish). It combines net institutional buying activity, ownership shift, marquee investor presence, and holder-count growth.
58 institutions opened new positions in MGNI during Q1 2026, while 66 fully exited. 54 added to existing positions and 177 trimmed.
MGNI institutional ownership fell by 26.28 percentage points quarter-over-quarter, with a net change of -8 holders.
The top 10 institutions account for 45.7% of all reported 13F value in MGNI, and the top 25 account for 70.9%.
All data is sourced from SEC Form 13F filings, which institutional investment managers with at least $100M in assets are required to file each quarter. We process every 13F filing from EDGAR and recompute the aggregates after each cycle. Insider transactions are sourced from Form 4 filings.
Magnite, Inc. (MGNI) Institutional Ownership