Rubicon Project Inc

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Rubicon Project Inc
TickerMGNI
CIK #0001595974
CUSIP55955D100
SectorTechnology - Services-Computer Programming, Data Processing, Etc.
Address12181 Bluff Creek Drive, 4th Floor, Los Angeles, CA 90094
Source [EDGAR]
CIK Filing 2011 - 2026
[0001595974] 10-K
[0001595974] 10-Q
[0001595974] 3
[0001595974] 4
[0001595974] 8-K
[0001595974] SC 13D
[0001595974] SC 13G
Form 13D/13G Filer Form 13D/13G Subject Filed % Owned
Vanguard Capital Management LLC Magnite Inc [2026-04-30] 0.0
Vanguard Portfolio Management LLC Magnite Inc [2026-04-29] 0.0
Capital Research Global Investors Magnite Inc [2026-02-12] 0.0
Wellington Management Group LLP Magnite Inc [2026-02-10] 0.0
FMR LLC Magnite Inc [2025-05-12] 0.0
Capital Research Global Investors Magnite Inc [2025-02-13] 0.0
FMR LLC Magnite Inc [2024-02-09] 0.0
Edenbrook Capital LLC Magnite Inc [2022-11-10] 5.17
Granahan Investment Management LLC Magnite Inc [2022-02-14] 6.44
Vanguard Group Inc Magnite Inc [2022-02-10] 8.97
FMR LLC Magnite Inc [2022-02-09] 0.0
Bertelsmann SE & Co KGAA Magnite Inc [2021-05-10] 9.6
BlackRock Inc Rubicon Project Inc [2020-02-07] 6.6
Outerbridge Capital Management LLC Rubicon Project Inc [2019-12-23] 5.51
Outerbridge Capital Management LLC Rubicon Project Inc [2019-12-02] 4.41
Dimensional Fund Advisors LP Rubicon Project Inc [2019-02-08] 5.06
BlackRock Inc Rubicon Project Inc [2018-02-01] 5.5
Divisar Capital Management LLC Rubicon Project Inc [2017-08-08] 5.1
Rubicon Project Inc Rubicon Project Inc [2016-02-16] 3.6
Bank of Montreal /Can/ Rubicon Project Inc [2016-02-16] 6.8454
PRIMECAP Management Co/CA/ Rubicon Project Inc [2015-12-07] 5.3
40 North Management LLC Rubicon Project Inc [2015-11-27] 6.5
Addante Frank Rubicon Project Inc [2015-04-09] 7.6
Clearstone Venture Partners III-A LP Rubicon Project Inc [2015-02-17] 17.2
News Corp Rubicon Project Inc [2015-02-13] 13.2
Mayfield XII Management LLC Rubicon Project Inc [2015-01-30] 11.4
Form 3/4/5 Filer 2011 - 2026
Buonasera David
Magnite Inc
Barrett Michael G
Buckley Sean Patrick
Knopper Douglas S
Caine Paul
Pearson David T
Lam Rachel
Rossman James
Harden Sarah Patricia
Spillane Robert F
Yu Diane
Gephart Brian
Saltz Aaron
Evans Katie Seitz
Day David
Soroca Adam Lee
Frankenberg Robert J
TROE Lisa L
Dove James Allen
Prusz Joseph R
Hughes Shawna
Kershaw Thomas
Filip Eve
Tuller Blima
Zagorski Mark
Addante Frank
Feldman Jonathan
Coleman Lewis W
Mandal Sumant
Copple Brian William
Raifman Gregory R
Patz Harry Jr
Richter James Neal
Tappin Todd L
Clearstone Venture Partners III-B a Delaware Multiple Serie
Clearstone Venture Partners III-A LP
Clearstone Venture Management III LLC
Vasan Robert T
Mayfield XII Management
Beck James T
Mayfield Principals Fund XII
Mayfield Associates Fund XII
Chaddha Navin
Mayfield XII A Delaware L P
MOHN JARL
News Corp
Insider Transaction (Form 3/4/5) Date Action Shares Price Value ($)
Soroca Adam Lee
Common Stock
2026-02-18 Sell 21,529 $12.00 258,348
Soroca Adam Lee
Common Stock
2026-02-15 Tax withheld 18,933 $11.70 221,516
Buonasera David
Common Stock
2026-02-15 Tax withheld 17,137 $11.70 200,503
Saltz Aaron
Common Stock
2026-02-15 Tax withheld 12,761 $11.70 149,304
Barrett Michael G
Common Stock
2026-02-15 Tax withheld 23,549 $11.70 275,523
Gephart Brian
Common Stock
2026-02-15 Tax withheld 6,149 $11.70 71,943
Day David
Common Stock
2026-02-15 Tax withheld 30,617 $11.70 358,219
Buckley Sean Patrick
Common Stock
2026-02-15 Tax withheld 26,942 $11.70 315,221
Evans Katie Seitz
Common Stock
2026-02-15 Tax withheld 27,428 $11.70 320,908
Evans Katie Seitz
Common Stock
2026-01-09 Option exercise 51,300 $0.00
Saltz Aaron
Common Stock
2026-01-09 Tax withheld 15,026 $16.17 242,970
Barrett Michael G
Common Stock
2026-01-09 Option exercise 213,750 $0.00
Barrett Michael G
Common Stock
2026-01-09 Tax withheld 109,742 $16.17 1,774,528
Buonasera David
Common Stock
2026-01-09 Option exercise 22,935 $0.00
Day David
Performance Stock Units · derivative
2026-01-09 Option exercise 72,675 $0.00
Soroca Adam Lee
Performance Stock Units · derivative
2026-01-09 Option exercise 51,300 $0.00
Buckley Sean Patrick
Common Stock
2026-01-09 Tax withheld 30,369 $16.17 491,067
Evans Katie Seitz
Performance Stock Units · derivative
2026-01-09 Option exercise 51,300 $0.00
Day David
Common Stock
2026-01-09 Tax withheld 35,169 $16.17 568,683
Buonasera David
Performance Stock Units · derivative
2026-01-09 Option exercise 22,935 $0.00
showing 20 of 200 most recent transactions
13F Ownership Over TimeHoldersShares Held
2026-03-31 297 136,769,081
2025-12-31 308 144,463,536
2025-09-30 323 144,707,968
2025-06-30 293 154,709,324
2025-03-31 299 139,672,498
2024-12-31 289 130,684,483
2024-09-30 283 126,030,183
2024-06-30 272 109,031,905
2024-03-31 238 108,450,862
2023-12-31 220 107,711,412
2023-09-30 218 108,212,399
2023-06-30 227 106,182,777
Form 13F Holdings
Firm Period DFND Voting Shares
Kopion Asset Management LLC [2026-06-30] SOLE 0 674,451
DBA Trading LLC [2026-06-30] SOLE 150,000 150,000
Moody National Bank Trust Division [2026-06-30] DFND 584 97,202
Cardinal Point Capital Management ULC [2026-06-30] SOLE 0 92,150
Ardsley Advisory Partners LP [2026-06-30] SOLE 57,500 57,500
Handelsbanken Fonder AB [2026-06-30] SOLE 0 47,300
Fulton Bank NA [2026-06-30] SOLE 33,041 33,041
Alaska Retirement Management Board [2026-06-30] SOLE 30,334 30,334
Linden Thomas Advisory Services LLC [2026-06-30] SOLE 0 26,206
Winthrop Advisory Group LLC [2026-06-30] SOLE 0 14,520
Wealth Enhancement Advisory Services LLC [2026-06-30] SOLE 147 14,161
HCR Wealth Advisors [2026-06-30] SOLE 13,000 13,000
Ledgewood Wealth Advisors LLC [2026-06-30] SOLE 0 12,577
1620 Investment Advisors Inc [2026-06-30] SOLE 9,097 9,097
Central Pacific Bank - Trust Division [2026-06-30] DFND 0 5,000
Versant Capital Management Inc [2026-06-30] SOLE 4,715 4,715
Rachor Investment Advisory Services LLC [2026-06-30] SOLE 0 4,164
Harbor Investment Advisory LLC [2026-06-30] SOLE 3,265 3,265
Gamma Investing LLC [2026-06-30] DFND 2,208 2,208
Owl Creek Wealth Partners LLC [2026-06-30] SOLE 0 660
Corecap Advisors LLC [2026-06-30] SOLE 0 524
Farther Finance Advisors LLC [2026-06-30] SOLE 0 308
Abound Wealth Management [2026-06-30] SOLE 0 176
True Wealth Design LLC [2026-06-30] SOLE 0 141
Fortitude Family Office LLC [2026-06-30] SOLE 130 130
Entrust Financial LLC [2026-06-30] SOLE 0 100
Physician Wealth Advisors Inc [2026-06-30] SOLE 0 53
JFS Wealth Advisors LLC [2026-06-30] SOLE 0 50
MassMutual Private Wealth & Trust FSB [2026-06-30] SOLE 11 11
Hughes Financial Services LLC [2026-06-30] SOLE 3 3
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