Latest Period
Q1 2026
Security Snapshot
MAGNITE, INC. - Common Stock (MGNI) Institutional Ownership
CUSIP: 55955D100
13F Institutional Holders and Ownership History from Q1 2019 to Q1 2026
Institutions Reporting
288
Shares (Excl. Options)
129,736,711
Price
$11.88
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- Type / Class
- Equity / Common Stock
- Symbol
- MGNI on Nasdaq
- Shares outstanding
- 143,436,829
- Price per share
- $12.92
- All holders as of 31 Mar 2026
- Q1 2026
- Total 13F shares
- 129,736,711
- Total reported value
- $1,541,982,530
- % of total 13F portfolios
- 0.01%
- Share change
- -6,371,296
- Value change
- -$103,454,458
- Number of holders
- 288
- Price from insider filings
- $12.92
Reported Shares, Excluding Options vs Price
Reported Value, Excluding Options
Total Investors
Quick Takeaways
- MGNI - MAGNITE, INC. - Common Stock is tracked under CUSIP 55955D100.
- 288 institutions reported positions in Q1 2026.
- 5 significant owners is listed from Schedule 13D/13G reporting.
What Changed
- Holder count moved from 301 to 288 between Q4 2025 and Q1 2026.
- Reported value moved from $2,218,533,134 to $1,541,982,530.
Why This Matters
- You can quickly see who holds this security, then open quarter and manager detail pages for full evidence.
- 13F and Schedule 13D/13G sections are kept together so you can cross-check institutional and beneficial ownership context.
Source Evidence
Source: SEC Form 13F
Open SEC Evidence
Latest holder context comes from 288 institutions filings for Q1 2026.
Investment Quick Answers
What is CUSIP 55955D100?
CUSIP 55955D100 identifies MGNI - MAGNITE, INC. - Common Stock in SEC 13F datasets.
Where can I see the latest institutional holders?
Review the Q1 2026 holders report and the ownership history table below.
Next ownership checks
Use the next link that matches the question you still need to answer about this security.
- Latest 13F filings when you want to inspect fresh institutional portfolio moves.
- Latest Schedule 13D/13G reports when you need large-owner changes outside the 13F cycle.
- All institutional ownership pages to compare this security with other holder-history pages.
Recent Quarterly Holder Reports
Open recent reporting periods for CUSIP 55955D100:
Significant Owners of MAGNITE, INC. - Common Stock (MGNI) based on Schedule 13D/G filings
| Filer | Ownership | Change % | Holdings Value | Net Change | Nb Shares | Change % | Reporting Name | Report Period |
|---|---|---|---|---|---|---|---|---|
| WELLINGTON MANAGEMENT GROUP LLP | 6% | $138,844,439 | 8,629,238 | Wellington Management Group LLP | 31 Dec 2025 | |||
| VANGUARD PORTFOLIO MANAGEMENT LLC | 5.4% | $93,256,456 | 7,849,870 | Vanguard Portfolio Management | 31 Mar 2026 | |||
| VANGUARD CAPITAL MANAGEMENT LLC | 5% | $86,525,949 | 7,283,329 | Vanguard Capital Management | 31 Mar 2026 | |||
| Capital Research Global Investors | 3.5% | -61% | $60,695,294 | -$95,511,000 | 5,020,289 | -61% | Capital Research Global Investors | 31 Mar 2026 |
| FMR LLC | 3.1% | -43% | $54,494,691 | -$43,735,587 | 4,507,419 | -45% | FMR LLC | 31 Mar 2026 |
As of 31 Mar 2026, 288 institutional investors reported holding 129,736,711 shares of MAGNITE, INC. - Common Stock (MGNI). This represents 90% of the company’s total 143,436,829 outstanding shares.
Top 25 Institutional Shareholders
The largest institutional shareholders of MAGNITE, INC. - Common Stock (MGNI) together control 65% of the company’s outstanding shares — a level of ownership often associated with strong institutional conviction and long‑term capital commitment.
| Institution | Ownership % | Shares Held | Share Change % | Portfolio % | Holdings Value |
|---|---|---|---|---|---|
| BlackRock, Inc. | 8.1% | 11,657,496 | +0.55% | 0% | $138,491,059 |
| WELLINGTON MANAGEMENT GROUP LLP | 6.4% | 9,191,077 | +6.5% | 0.02% | $109,189,995 |
| VANGUARD PORTFOLIO MANAGEMENT LLC | 5.4% | 7,726,205 | 0% | 0% | $91,787,315 |
| VANGUARD CAPITAL MANAGEMENT LLC | 4.3% | 6,190,403 | 0% | 0% | $73,541,988 |
| Capital Research Global Investors | 3.5% | 5,020,289 | -61% | 0.01% | $59,641,033 |
| Boston Partners | 3.3% | 4,719,863 | +15% | 0.06% | $56,078,770 |
| AMERICAN CENTURY COMPANIES INC | 3.2% | 4,626,816 | -12% | 0.03% | $54,966,590 |
| FMR LLC | 3.1% | 4,507,419 | -33% | 0% | $53,548,133 |
| DIMENSIONAL FUND ADVISORS LP | 2.8% | 3,983,674 | +10% | 0.01% | $47,321,837 |
| Nuveen, LLC | 2.5% | 3,590,025 | +1.7% | 0.01% | $42,649,497 |
| GEODE CAPITAL MANAGEMENT, LLC | 2.5% | 3,553,790 | +3.5% | 0% | $42,226,958 |
| Nine Ten Capital Management LLC | 2.4% | 3,481,283 | +16% | 13% | $41,358,000 |
| STATE STREET CORP | 2.2% | 3,163,139 | +0.67% | 0% | $37,578,091 |
| Edenbrook Capital, LLC | 2% | 2,798,036 | +0.36% | 17% | $33,240,667 |
| Granahan Investment Management, LLC | 1.8% | 2,553,413 | -18% | 1.5% | $30,334,546 |
| Ophir Asset Management Pty Ltd | 1.5% | 2,118,016 | -11% | 2.9% | $25,162,030 |
| 325 CAPITAL LLC | 1.4% | 2,005,387 | 0% | 8.7% | $23,823,998 |
| KENNEDY CAPITAL MANAGEMENT LLC | 1.2% | 1,753,542 | +22% | 0.44% | $20,832,079 |
| JANE STREET GROUP, LLC | 1.2% | 1,668,160 | +339% | 0.02% | $19,817,740 |
| No Street GP LP | 1.1% | 1,628,248 | +10% | 1.3% | $19,343,586 |
| Schonfeld Strategic Advisors LLC | 1.1% | 1,605,041 | +106% | 0.16% | $19,067,886 |
| GOLDMAN SACHS GROUP INC | 1% | 1,500,852 | -15% | 0% | $17,830,121 |
| Balyasny Asset Management L.P. | 1% | 1,500,443 | +72% | 0.04% | $17,825,263 |
| ROYCE & ASSOCIATES LP | 0.95% | 1,365,489 | +17% | 0.16% | $16,222,009 |
| Maestria Partners LLC | 0.95% | 1,363,505 | 0% | 5.9% | $16,198,439 |
Institutional Holders of MAGNITE, INC. - Common Stock (MGNI) across Reporting Periods
| Period | Reported Shares, Excl. Options | Value, Excl. Options | Value Change | Price (Median) | Investors |
|---|---|---|---|---|---|
| 2026 Q1 | 129,736,711 | $1,541,982,530 | -$103,454,458 | $11.88 | 288 |
| 2025 Q4 | 136,686,832 | $2,218,533,134 | -$66,065,749 | $16.23 | 301 |
| 2025 Q3 | 138,012,684 | $3,003,860,929 | -$207,225,719 | $21.78 | 313 |
| 2025 Q2 | 146,964,373 | $3,543,069,968 | +$406,190,715 | $24.12 | 285 |
| 2025 Q1 | 132,644,878 | $1,513,348,970 | +$97,506,469 | $11.41 | 290 |
| 2024 Q4 | 123,449,236 | $1,965,951,862 | +$42,368,020 | $15.92 | 283 |
| 2024 Q3 | 119,561,299 | $1,654,115,115 | +$216,068,704 | $13.85 | 279 |
| 2024 Q2 | 104,326,333 | $1,386,459,925 | +$39,957,238 | $13.29 | 266 |
| 2024 Q1 | 102,110,845 | $1,097,564,621 | -$5,361,702 | $10.75 | 230 |
| 2023 Q4 | 102,653,022 | $958,824,603 | -$4,019,427 | $9.34 | 215 |
| 2023 Q3 | 103,476,989 | $780,247,255 | -$17,837,826 | $7.54 | 208 |
| 2023 Q2 | 101,048,317 | $1,380,031,436 | +$74,884,448 | $13.65 | 217 |
| 2023 Q1 | 96,353,092 | $892,115,344 | +$22,211,875 | $9.26 | 217 |
| 2022 Q4 | 93,373,687 | $988,829,597 | -$97,935,020 | $10.59 | 228 |
| 2022 Q3 | 103,432,133 | $679,628,120 | +$93,907,627 | $6.57 | 201 |
| 2022 Q2 | 87,980,237 | $781,403,356 | -$17,395,213 | $8.88 | 214 |
| 2022 Q1 | 88,698,180 | $1,171,861,875 | -$35,248,615 | $13.21 | 215 |
| 2021 Q4 | 89,542,528 | $1,566,754,035 | -$140,798,799 | $17.50 | 238 |
| 2021 Q3 | 90,069,072 | $2,521,283,357 | +$118,150,307 | $28.00 | 270 |
| 2021 Q2 | 85,375,930 | $2,889,381,654 | -$89,507,112 | $33.84 | 264 |
| 2021 Q1 | 86,041,634 | $3,579,979,338 | +$418,396,545 | $41.61 | 271 |
| 2020 Q4 | 76,786,392 | $2,357,551,419 | +$83,965,902 | $30.71 | 235 |
| 2020 Q3 | 83,209,025 | $577,796,330 | +$477,632,041 | $6.94 | 168 |
| 2020 Q2 | 14,428,175 | $96,233,000 | +$96,233,000 | $6.67 | 10 |
| 2020 Q1 | 203 | $7,000 | $34.48 | 1 | |
| 2019 Q4 | 203 | $7,000 | $34.48 | 1 | |
| 2019 Q3 | 203 | $7,000 | $34.48 | 1 | |
| 2019 Q2 | 203 | $7,000 | $34.48 | 1 | |
| 2019 Q1 | 203 | $7,000 | $34.48 | 1 |