MAGNITE INC MGNI
COM · Common Stock · CUSIP 55955D100 · ISIN US55955D1000
American advertising technology and real-time bidding, serving as ad exchange
- SectorTechnology
- IndustryServices-Computer Programming, Data Processing, Etc.
- HeadquartersNew York, NY
- Founded2007
- Websitemagnite.com
- FilingsSEC EDGAR
* Summed across managers. Shares that two managers' reports both contain – a subsidiary's holdings that its parent's report includes too, or a sub-adviser's in its client's – are counted once ($5.1m this quarter). Holder counts are more reliable. Shares outstanding: 143.4m as of 2026-07-29, from the company's own SEC filing; the percentage can still exceed 100%: lent-out shares are counted by the lender and the buyer, and some reports overlap without saying so. Implied quarter-end price ≈ $18.97. Options: 17 managers hold calls ($85.8m notional), 12 hold puts ($80.2m).
Trends to Q2 2026
Institutional holders
Managers reporting a position, each quarter
Numbers
| Quarter | Holders |
|---|---|
| Q3 2022 | 218 |
| Q4 2022 | 230 |
| Q1 2023 | 223 |
| Q2 2023 | 225 |
| Q3 2023 | 215 |
| Q4 2023 | 217 |
| Q1 2024 | 232 |
| Q2 2024 | 269 |
| Q3 2024 | 280 |
| Q4 2024 | 286 |
| Q1 2025 | 295 |
| Q2 2025 | 288 |
| Q3 2025 | 317 |
| Q4 2025 | 304 |
| Q1 2026 | 297 |
| Q2 2026 | 310 |
Buyers vs sellers
Managers adding to or starting a position, vs cutting or selling out
Numbers
| Quarter | Bought or added | Cut or sold out |
|---|---|---|
| Q3 2024 | 146 | 108 |
| Q4 2024 | 137 | 133 |
| Q1 2025 | 155 | 136 |
| Q2 2025 | 150 | 156 |
| Q3 2025 | 152 | 164 |
| Q4 2025 | 167 | 149 |
| Q1 2026 | 159 | 133 |
| Q2 2026 | 167 | 126 |
Calls vs puts
Options held, notional value, last 4 quarters. P/C = puts ÷ calls
Numbers
| Quarter | Calls | Puts | P/C |
|---|---|---|---|
| Q3 2025 | $136.4m | $99.8m | 0.73 |
| Q4 2025 | $98.0m | $69.7m | 0.71 |
| Q1 2026 | $26.7m | $52.5m | 1.97 |
| Q2 2026 | $85.8m | $80.2m | 0.94 |
Biggest buyers
| FMR LLC | Added | +3.3m |
| CANADA PENSION PLAN INVESTMENT BOARD | Added | +2.9m |
| 325 CAPITAL LLC | Added | +1.4m |
| Park West Asset Management LLC | Added | +1.4m |
| Qube Research & Technologies Ltd | Added | +1.3m |
| DIMENSIONAL FUND ADVISORS LP | Added | +1.3m |
| MORGAN STANLEY | Added | +1.1m |
| BlackRock, Inc. | Added | +1.1m |
| First Eagle Investment Management, LLC | Added | +891.3k |
| Edenbrook Capital, LLC | Added | +757.6k |
Biggest sellers
| WELLINGTON MANAGEMENT GROUP LLP | Reduced | -3.1m |
| No Street GP LP | Sold out | -1.6m |
| Capital Research Global Investors | Reduced | -1.2m |
| Schonfeld Strategic Advisors LLC | Reduced | -1.0m |
| Balyasny Asset Management L.P. | Reduced | -833.9k |
| Ophir Asset Management Pty Ltd | Reduced | -668.0k |
| Man Group plc | Reduced | -610.9k |
| CITADEL ADVISORS LLC | Reduced | -580.0k |
| Pacer Advisors, Inc. | Sold out | -501.6k |
| MILLENNIUM MANAGEMENT LLC | Reduced | -469.6k |
Biggest calls
| Walleye Trading LLC | Added | $15.7m827.7k shares |
| PICTON MAHONEY ASSET MANAGEMENT | New | $14.2m750.0k shares |
| BANK OF MONTREAL /CAN/ | New | $14.0m740.0k shares |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Added | $8.7m457.7k shares |
| Caption Management, LLC | New | $6.7m354.0k shares |
| CITADEL ADVISORS LLC | Added | $6.4m337.9k shares |
| IMC-Chicago, LLC | Added | $5.0m262.7k shares |
| Park West Asset Management LLC | New | $4.7m250.0k shares |
| GROUP ONE TRADING LLC | Added | $3.5m184.3k shares |
| TUDOR INVESTMENT CORP ET AL | Added | $2.4m125.2k shares |
Biggest puts
| Caption Management, LLC | Unchanged | $28.5m1.5m shares |
| CITADEL ADVISORS LLC | Added | $22.2m1.2m shares |
| Squarepoint Ops LLC | Reduced | $11.2m590.2k shares |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Added | $4.8m254.0k shares |
| Walleye Trading LLC | Reduced | $4.7m246.2k shares |
| BANK OF MONTREAL /CAN/ | New | $2.6m135.0k shares |
| IMC-Chicago, LLC | Added | $2.6m134.8k shares |
| JANE STREET GROUP, LLC | Added | $2.5m131.1k shares |
| GROUP ONE TRADING LLC | Added | $444.1k23.4k shares |
| SIMPLEX TRADING, LLC | Added | $391.0k20.6k shares |
Options at notional value: the value of the shares the contracts control, as filers report them, not what the options cost. Not included in the holders, shares or buying above.
Major shareholders (over 5%)
Anyone who owns more than 5% of a class of the company's shares has to say so: on Schedule 13D if they may try to influence or control the company, on 13G if they're a passive investor, and update it as the stake changes. Each holder's latest filing, from 19 Dec 2024 on; percentages are of the share class, as the holder worked them out.
| Holder | Stake |
|---|---|
| VANGUARD PORTFOLIO MANAGEMENT LLC 13G · institution new · filed 2026-04-29 | 5.4% |
| FMR LLC 13G · institution +2.3 pts · filed 2026-08-06 | 5.4% |
| VANGUARD CAPITAL MANAGEMENT LLC 13G · institution new · filed 2026-04-30 | 5.0% |
Fell to 5% or below in the last year: WELLINGTON MANAGEMENT GROUP LLP (4.2%, 2026-08-13), Capital Research Global Investors (3.5%, 2026-05-14), VANGUARD GROUP INC (0.0%, 2026-03-27; now reported by VANGUARD PORTFOLIO MANAGEMENT LLC)
Insider purchases and sales since 1 Apr 2026
Shares bought or sold by the company's own officers, directors and 10% owners, in the open market or privately, as they reported to the SEC on Form 4 (due within two business days of the trade). Grants, option exercises, shares withheld for tax and gifts aren't included.
Officers and directors buying vs selling
Number of people, by quarter (10% owners not included)
Numbers
| Quarter | Buying | Bought | Selling | Sold | Sold under a plan |
|---|---|---|---|---|---|
| Q4 2024 | 0 | — | 9 | $7.0m | $6.8m |
| Q1 2025 | 0 | — | 8 | $5.8m | $5.7m |
| Q2 2025 | 0 | — | 12 | $17.7m | $17.0m |
| Q3 2025 | 0 | — | 11 | $11.2m | $6.3m |
| Q4 2025 | 0 | — | 4 | $795.8k | $618.0k |
| Q1 2026 | 0 | — | 1 | $258.3k | $258.3k |
| Q2 2026 | 0 | — | 6 | $8.0m | $7.8m |
| Q3 2026 | 0 | — | 11 | $17.6m | $16.8m |
| Date | Insider | Trade | Value |
|---|---|---|---|
| 2026-09-17 | Knopper Douglas S Director | Sold plan | $981.2k37.3k shares |
| 2026-09-17 | Caine Paul Director | Sold plan | $198.8k7.5k shares |
| 2026-09-14 | Spillane Robert F Director | Sold | $246.2k10.4k shares |
| 2026-09-14 | Buonasera David CHIEF TECHNOLOGY OFFICER | Sold plan | $28.0k1.2k shares |
| 2026-09-11 | Evans Katie Seitz Officer | Sold plan | $335.9k14.0k shares |
| 2026-09-10 | Saltz Aaron CHIEF LEGAL OFFICER | Sold plan | $936.4k40.0k shares |
| 2026-09-10 | Caine Paul Director | Sold plan | $117.7k5.0k shares |
| 2026-09-09 | Evans Katie Seitz Officer | Sold plan | $260.4k11.1k shares |
| 2026-09-08 | Evans Katie Seitz Officer | Sold plan | $762.9k32.3k shares |
| 2026-09-02 | Buonasera David CHIEF TECHNOLOGY OFFICER | Sold plan | $26.1k1.0k shares |
| 2026-09-01 | Buonasera David CHIEF TECHNOLOGY OFFICER | Sold plan | $125.8k5.4k shares |
| 2026-08-28 | Harden Sarah Patricia Director | Sold plan | $442.5k18.4k shares |
| 2026-08-26 | Harden Sarah Patricia Director | Sold plan | $712.1k30.6k shares |
| 2026-08-18 | Buckley Sean Patrick Officer | Sold plan | $69.0k2.8k shares |
| 2026-08-17 | Buckley Sean Patrick Officer | Sold plan | $201.1k8.3k shares |
| 2026-08-14 | Caine Paul Director | Sold plan | $187.5k7.5k shares |
| 2026-08-10 | Gephart Brian CHIEF ACCOUNTING OFFICER | Sold | $308.0k12.5k shares |
| 2026-08-10 | Lam Rachel Director | Sold | $241.6k10.0k shares |
| 2026-08-10 | Caine Paul Director | Sold plan | $121.8k5.0k shares |
| 2026-08-06 | BARRETT MICHAEL G. CEO, director | Sold plan | $6.7m294.0k shares |
| 2026-08-06 | Buckley Sean Patrick Officer | Sold plan | $1.6m67.2k shares |
| 2026-08-06 | Knopper Douglas S Director | Sold plan | $848.3k37.3k shares |
| 2026-08-06 | Evans Katie Seitz Officer | Sold plan | $480.0k20.0k shares |
| 2026-08-06 | Buonasera David CHIEF TECHNOLOGY OFFICER | Sold plan | $179.5k7.6k shares |
| 2026-07-15 | BARRETT MICHAEL G. CEO, director | Sold plan | $785.4k38.6k shares |
| 2026-07-10 | Caine Paul Director | Sold plan | $103.2k5.0k shares |
| 2026-07-07 | Buckley Sean Patrick Officer | Sold plan | $404.5k19.2k shares |
| 2026-07-07 | Buonasera David CHIEF TECHNOLOGY OFFICER | Sold plan | $25.7k1.2k shares |
| 2026-07-01 | Buonasera David CHIEF TECHNOLOGY OFFICER | Sold plan | $187.5k9.4k shares |
| 2026-06-29 | BARRETT MICHAEL G. CEO, director | Sold plan | $1.5m75.0k shares |
The latest 30 of 41 trades.
Their holding: how much the trade added to or took from the insider's holding (direct, or the trust or fund named). The same trade is sometimes reported by more than one insider, such as a fund and the director who represents it; totals count it once. A value is left blank where the reported price is far from the market price (usually a typo).
Holders, Q2 2026
| Manager | Shares | Change |
|---|---|---|
| BlackRock, Inc. 0.00% of their portfolio | 12.7m $241.3m | Added +1.1m |
| VANGUARD PORTFOLIO MANAGEMENT LLC 0.01% of their portfolio | 8.2m $155.6m | Added +471.1k |
| FMR LLC 0.01% of their portfolio | 7.8m $147.3m | Added +3.3m |
| VANGUARD CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 6.2m $118.2m | Added +34.8k |
| WELLINGTON MANAGEMENT GROUP LLP 0.02% of their portfolio | 6.0m $114.7m | Reduced -3.1m |
| DIMENSIONAL FUND ADVISORS LP 0.02% of their portfolio | 5.3m $99.8m | Added +1.3m |
| Boston Partners 0.09% of their portfolio | 5.0m $95.9m | Added +294.0k |
| AMERICAN CENTURY COMPANIES INC 0.04% of their portfolio | 4.6m $87.7m | Reduced -4.1k |
| Capital Research Global Investors 0.01% of their portfolio | 3.9m $73.4m | Reduced -1.2m |
| Nuveen, LLC 0.02% of their portfolio | 3.8m $72.0m | Added +204.8k |
| GEODE CAPITAL MANAGEMENT, LLC 0.00% of their portfolio | 3.8m $71.9m | Added +236.2k |
| Edenbrook Capital, LLC 23.59% of their portfolio | 3.6m $67.5m | Added +757.6k |
| STATE STREET CORP 0.00% of their portfolio | 3.5m $67.0m | Added +364.9k |
| 325 CAPITAL LLC 15.44% of their portfolio | 3.4m $64.8m | Added +1.4m |
| Nine Ten Capital Management LLC 19.26% of their portfolio | 3.3m $61.9m | Reduced -220.0k |
| Granahan Investment Management, LLC 2.09% of their portfolio | 3.1m $58.5m | Added +529.8k |
| CANADA PENSION PLAN INVESTMENT BOARD 0.03% of their portfolio | 3.0m $56.8m | Added +2.9m |
| JANE STREET GROUP, LLC 0.03% of their portfolio | 2.2m $41.7m | Added +531.0k |
| Park West Asset Management LLC 2.59% of their portfolio | 2.0m $38.0m | Added +1.4m |
| MORGAN STANLEY 0.00% of their portfolio | 2.0m $37.8m | Added +1.1m |
| Qube Research & Technologies Ltd 0.04% of their portfolio | 2.0m $37.1m | Added +1.3m |
| Blue Grotto Capital, LLC 2.70% of their portfolio | 1.7m $32.4m | Added +378.0k |
| KENNEDY CAPITAL MANAGEMENT LLC 0.56% of their portfolio | 1.7m $31.6m | Reduced -86.7k |
| NORTHERN TRUST CORP 0.00% of their portfolio | 1.6m $29.5m | Added +230.8k |
| ROYCE & ASSOCIATES LP 0.23% of their portfolio | 1.5m $28.0m | Added +107.9k |
| GOLDMAN SACHS GROUP INC 0.00% of their portfolio | 1.5m $27.8m | Reduced -34.2k |
| Ophir Asset Management Pty Ltd 2.26% of their portfolio | 1.5m $27.5m | Reduced -668.0k |
| First Eagle Investment Management, LLC 0.02% of their portfolio | 1.3m $25.5m | Added +891.3k |
| VICTORY CAPITAL MANAGEMENT INC 0.01% of their portfolio | 1.2m $23.4m | Reduced -31.1k |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.00% of their portfolio | 1.2m $22.8m | Added +22.8k |
| BANK OF AMERICA CORP /DE/ 0.00% of their portfolio | 1.2m $22.4m | Added +56.6k |
| GRIZZLYROCK CAPITAL, LLC 15.46% of their portfolio | 1.2m $22.1m | Reduced -74.1k |
| Bank of New York Mellon Corp 0.00% of their portfolio | 1.2m $22.1m | Added +24.0k |
| Maestria Partners LLC 7.65% of their portfolio | 1.2m $22.0m | Reduced -205.1k |
| Meros Investment Management, LP 5.97% of their portfolio | 991.3k $18.8m | Reduced -1.0k |
| VANGUARD FIDUCIARY TRUST CO 0.00% of their portfolio | 989.1k $18.8m | Reduced -8.0k |
| MILLENNIUM MANAGEMENT LLC 0.01% of their portfolio | 764.8k $14.5m | Reduced -469.6k |
| QVT Financial LP 0.91% of their portfolio | 747.4k $14.2m | Added +293.5k |
| UBS Group AG 0.00% of their portfolio | 746.4k $14.2m | Added +296.0k |
| OBERWEIS ASSET MANAGEMENT INC/ 0.29% of their portfolio | 735.0k $14.0m | Added +87.4k |
| SILVERCREST ASSET MANAGEMENT GROUP LLC 0.09% of their portfolio | 707.7k $13.4m | Added +91.7k |
| PICTON MAHONEY ASSET MANAGEMENT 0.12% of their portfolio | 691.5k $13.1m | Added +48.4k |
| Kopion Asset Management, LLC 8.09% of their portfolio | 674.5k $12.8m | Reduced -181.5k |
| Balyasny Asset Management L.P. 0.02% of their portfolio | 666.6k $12.7m | Reduced -833.9k |
| AMERIPRISE FINANCIAL INC 0.00% of their portfolio | 619.6k $11.8m | New |
| S SQUARED TECHNOLOGY, LLC 3.34% of their portfolio | 567.9k $10.8m | Added +165.0k |
| Schonfeld Strategic Advisors LLC 0.06% of their portfolio | 562.2k $10.7m | Reduced -1.0m |
| NOMURA ASSET MANAGEMENT CO LTD 0.02% of their portfolio | 553.9k $10.5m | Reduced -40.0k |
| BANK OF MONTREAL /CAN/ 0.00% of their portfolio | 533.8k $10.1m | New |
| KING LUTHER CAPITAL MANAGEMENT CORP 0.04% of their portfolio | 503.6k $9.6m | Reduced -27.5k |
| PRINCIPAL FINANCIAL GROUP INC 0.00% of their portfolio | 497.5k $9.4m | Added +51.6k |
| EVR Research LP 4.50% of their portfolio | 480.0k $9.1m | New |
| CITADEL ADVISORS LLC 0.01% of their portfolio | 472.9k $9.0m | Reduced -580.0k |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP 0.01% of their portfolio | 461.8k $8.8m | Added +154.0k |
| Manatuck Hill Partners, LLC 2.83% of their portfolio | 450.0k $8.5m | Added +140.0k |
| Jump Financial, LLC 0.07% of their portfolio | 428.0k $8.1m | New |
| JPMORGAN CHASE & CO 0.00% of their portfolio | 407.0k $7.9m | Reduced -79.8k |
| NORDEA INVESTMENT MANAGEMENT AB 0.01% of their portfolio | 386.3k $7.4m | Reduced -34.7k |
| COMMONWEALTH EQUITY SERVICES, LLC 0.01% of their portfolio | 368.2k $7.0m | Added +8.6k |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC 0.00% of their portfolio | 364.6k $6.9m | Added +41.6k |
| MARSHALL WACE, LLP 0.01% of their portfolio | 341.9k $6.5m | Added +299.4k |
| Trexquant Investment LP 0.04% of their portfolio | 333.4k $6.3m | New |
| Alyeska Investment Group, L.P. 0.02% of their portfolio | 326.8k $6.2m | New |
| 1492 Capital Management LLC 1.78% of their portfolio | 317.8k $6.0m | Reduced -22.8k |
| HARBOR CAPITAL ADVISORS, INC. 0.40% of their portfolio | 312.4k $5.9m | Reduced -12.9k |
| RAYMOND JAMES FINANCIAL INC 0.00% of their portfolio | 309.9k $5.9m | Added +18.2k |
| Swiss National Bank 0.00% of their portfolio | 289.7k $5.5m | Added +5.4k |
| Lisanti Capital Growth, LLC 1.21% of their portfolio | 289.0k $5.5m | Reduced -20.4k |
| RICE HALL JAMES & ASSOCIATES, LLC 0.26% of their portfolio | 283.9k $5.4m | Added +91.1k |
| ExodusPoint Capital Management, LP 0.05% of their portfolio | 271.9k $5.2m | Added +122.7k |
| Norwood Investment Partners, LP 6.16% of their portfolio | 235.0k $4.5m | Reduced -50.0k |
| BARCLAYS PLC 0.00% of their portfolio | 233.7k $4.4m | Added +53.0k |
| Squarepoint Ops LLC 0.01% of their portfolio | 230.2k $4.4m | Reduced -70.7k |
| Senvest Management, LLC 0.12% of their portfolio | 224.1k $4.3m | Unchanged |
| Invesco Ltd. 0.00% of their portfolio | 222.2k $4.2m | Reduced -39.2k |
| Hilton Capital Management, LLC 0.28% of their portfolio | 219.4k $4.2m | Added +11.3k |
| Pillsbury Lake Capital LLC 1.13% of their portfolio | 217.8k $4.1m | New |
| Cerity Partners LLC 0.00% of their portfolio | 201.0k $3.8m | Added +99.8k |
| PRICE T ROWE ASSOCIATES INC /MD/ 0.00% of their portfolio | 199.4k $3.8m | Added +34.0k |
| VOYA INVESTMENT MANAGEMENT LLC 0.00% of their portfolio | 196.7k $3.7m | Reduced -13.9k |
| RHUMBLINE ADVISERS 0.00% of their portfolio | 195.8k $3.7m | Added +15.8k |
| Occam Crest Management LP 2.12% of their portfolio | 195.0k $3.8m | New |
| GREAT LAKES ADVISORS, LLC 0.03% of their portfolio | 176.6k $3.4m | New |
| AQR CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 176.6k $3.4m | Added +55.4k |
| STATE OF WISCONSIN INVESTMENT BOARD 0.01% of their portfolio | 172.3k $3.3m | Reduced -13.2k |
| CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM 0.00% of their portfolio | 172.0k $3.3m | Reduced -4.5k |
| DEAN INVESTMENT ASSOCIATES, LLC 0.42% of their portfolio | 167.9k $3.2m | New |
| Legato Capital Management LLC 0.26% of their portfolio | 166.9k $3.2m | Added +82.1k |
| Tidal Investments LLC 0.01% of their portfolio | 165.8k $3.1m | Added +32.1k |
| SEI INVESTMENTS CO 0.00% of their portfolio | 165.6k $3.1m | Reduced -185.3k |
| DEUTSCHE BANK AG\ 0.00% of their portfolio | 165.0k $3.1m | Added +25.4k |
| LPL Financial LLC 0.00% of their portfolio | 163.8k $3.1m | Added +8.4k |
| Quantinno Capital Management LP 0.00% of their portfolio | 161.8k $3.1m | Added +33.6k |
| P.A.W. CAPITAL CORP 2.33% of their portfolio | 160.0k $3.0m | Reduced -10.0k |
| CLOUGH CAPITAL PARTNERS L P 0.25% of their portfolio | 159.6k $3.0m | New |
| DBA TRADING, LLC 0.90% of their portfolio | 150.0k $1.8m | Unchanged |
| Concentric Capital Strategies, LP 0.17% of their portfolio | 146.7k $2.8m | New |
| Caption Management, LLC 0.10% of their portfolio | 145.6k $2.8m | Reduced -259.5k |
| ALLIANCEBERNSTEIN L.P. 0.00% of their portfolio | 144.8k $1.7m | Reduced -78.3k |
| VANGUARD ASSET MANAGEMENT, Ltd 0.00% of their portfolio | 140.4k $2.7m | Added +14.1k |