Ticker · CUSIP 55955D100

MGNI

MAGNITE INC

Communication Services·Advertising Agencies

···Share

Holders (tracked)

Combined shares

12,396,725

Combined value

$201.20M

Last close

$13.71

Quarter

2025Q4

Price is -15.5% vs the avg quarter-end implied price across tracked holders.

Price · 1Y$13.71+2.58 (+23.18%)H $26.52 · L $11.01 · Avg Vol 2.7M

Position opened

Tracked holders · last 8 quarters

Flat over the last 8 quarters.

SEC event timeline

24 events

Ken Griffin (Citadel Advisors) added2026-02-17
+374,757 shares · 2025Q4
Position
D.E. Shaw & Co. exited2026-02-17
−211,433 shares · 2025Q4
Position
Two Sigma Investments added2026-02-17
+62,981 shares · 2025Q4
Position
Izzy Englander (Millennium Mgmt) trimmed2026-02-17
−652,605 shares · 2025Q4
Position
Paul Tudor Jones (Tudor Investment) opened position2026-02-17
+34,674 shares · 2025Q4
Position
Wellington Management added2026-02-17
+3,484,689 shares · 2025Q4
Position
AQR Capital Management added2026-02-17
+49,464 shares · 2025Q4
Position
Steve Cohen (Point72) exited2026-02-17
−305,316 shares · 2025Q4
Position
T. Rowe Price trimmed2026-02-17
−1,836,010 shares · 2025Q4
Position
Ray Dalio (Bridgewater Associates) trimmed2026-02-13
−484 shares · 2025Q4
Position
Mario Gabelli (GAMCO) trimmed2026-02-05
−11,990 shares · 2025Q4
Position
First Eagle Investment Management trimmed2026-02-04
−279,000 shares · 2025Q4
Position
AQR Capital Management added2025-11-14
+27,111 shares · 2025Q3
Position
Izzy Englander (Millennium Mgmt) opened position2025-11-14
+676,349 shares · 2025Q3
Position
Steve Cohen (Point72) opened position2025-11-14
+305,316 shares · 2025Q3
Position
Two Sigma Investments added2025-11-14
+62,605 shares · 2025Q3
Position
D.E. Shaw & Co. added2025-11-14
+179,486 shares · 2025Q3
Position
T. Rowe Price added2025-11-14
+2,429,904 shares · 2025Q3
Position
Wellington Management trimmed2025-11-14
−303,288 shares · 2025Q3
Position
Norges Bank (Norway SWF) exited2025-11-13
−108,716 shares · 2025Q3
Position
Ray Dalio (Bridgewater Associates) opened position2025-11-13
+145,671 shares · 2025Q3
Position
Mario Gabelli (GAMCO) trimmed2025-11-12
−3,114 shares · 2025Q3
Position
First Eagle Investment Management trimmed2025-11-12
−42,676 shares · 2025Q3
Position
Norges Bank (Norway SWF) trimmed2025-11-12
−121,728 shares · 2024Q3
Position

Insider activity

No insider transactions in the last 30 days.

View full insider history for MGNI →

Follow-the-investor returns

If you'd copied each holder of MGNI…

Cost basis inferred from each manager's quarter-over-quarter position changes. Sorted by % return on the position they're still holding.

Investor	First in	Cost basis	Return	Position value today
Wellington Management	2020Q3	$13.59	+0.9%	$118.3M
Mario Gabelli (GAMCO)	2024Q2	$13.82	-0.8%	$610K
First Eagle Investment Management	2022Q2	$14.28	-4.0%	$4.1M
Paul Tudor Jones (Tudor Investment)	2020Q4	$15.99	-14.2%	$1.2M
Paul Tudor Jones (Tudor Investment)	2020Q4	$15.99	-14.2%	$1.2M
Paul Tudor Jones (Tudor Investment)	2020Q4	$15.99	-14.2%	$1.2M
Ken Griffin (Citadel Advisors)	2020Q3	$19.18	-28.5%	$7.5M
Ken Griffin (Citadel Advisors)	2020Q3	$19.18	-28.5%	$7.5M
Ken Griffin (Citadel Advisors)	2020Q3	$19.18	-28.5%	$7.5M
AQR Capital Management	2020Q3	$19.83	-30.9%	$1.3M
Izzy Englander (Millennium Mgmt)	2020Q3	$20.08	-31.7%	$326K
Izzy Englander (Millennium Mgmt)	2020Q3	$20.08	-31.7%	$326K
Steve Cohen (Point72)	2024Q1	$20.52	-33.2%	$322K
Two Sigma Investments	2021Q1	$20.65	-33.6%	$5.0M
T. Rowe Price	2020Q4	$21.70	-36.8%	$9.8M
Ray Dalio (Bridgewater Associates)	2025Q3	$21.78	-37.1%	$2.0M

Who moved on this name in 2025Q4

Position changes reported for the latest quarter, grouped by direction.

New positions1

Paul Tudor Jones (Tudor Investment)
+34,674
$563K

Added to4

Wellington Management
+3,484,689
$56.6M
Ken Griffin (Citadel Advisors)
+374,757
$6.1M
Two Sigma Investments
+62,981
$1.0M
AQR Capital Management
+49,464
$803K

Trimmed5

Izzy Englander (Millennium Mgmt)
−652,605
$10.6M
First Eagle Investment Management
−279,000
$4.5M
Mario Gabelli (GAMCO)
−11,990
$195K
T. Rowe Price
−1,836,010
$30K
Ray Dalio (Bridgewater Associates)
−484
$8K

Exited2

Steve Cohen (Point72)
−305,316
$6.6M
D.E. Shaw & Co.
−211,433
$4.6M

Institutional ownership over time

Distinct super-investors holding this ticker · combined dollar value, by quarter.

Quarter	Holders	Shares	Combined value	Δ holders
2022Q1	11	13,972,029	$15.90B	—
2022Q2	13	13,994,823	$10.66B	+2
2022Q3	13	14,098,824	$92.6M	—
2022Q4	13	14,410,331	$152.6M	—
2023Q1	11	14,086,932	$130.4M	-2
2023Q2	12	14,280,831	$194.9M	+1
2023Q3	11	12,281,561	$92.6M	-1
2023Q4	9	12,352,594	$115.4M	-2
2024Q1	11	14,665,377	$157.7M	+2
2024Q2	12	14,469,887	$192.3M	+1
2024Q3	12	9,135,496	$126.5M	—
2024Q4	13	2,470,479	$39.3M	+1
2025Q1	12	8,295,590	$94.7M	-1
2025Q2	11	8,258,991	$199.2M	-1
2025Q3	16	11,074,798	$241.2M	+5
2025Q4	16	12,396,725	$201.2M	—

Who owns MGNI

16 super-investors · 2025Q4

Tracked stake

12.40M

Combined value

$201M

% of shares outstanding

—

shares-out unknown

Quarter action mix

New3Added6Trim6Sold1

#	Manager	Shares	Value	% of book	Last action
1	Wellington Management	8.63M	$140M	0.0%	Added+3.48M
2	Ken Griffin Citadel Advisors	760.2K	$12M	0.0%	Added+374.8K
3	T. Rowe Price	711.5K	$12M	0.0%	Trim−1.84M
4	Ken Griffin Citadel Advisors	544.3K	$9M	0.0%	Added+374.8K
5	Ken Griffin Citadel Advisors	438.2K	$7M	0.0%	Added+374.8K
6	Two Sigma Investments	363.4K	$6M	0.0%	Added+63.0K
7	First Eagle Investment Management	296.4K	$5M	0.0%	Trim−279.0K
8	Paul Tudor Jones Tudor Investment	177.1K	$3M	0.0%	New+34.7K
9	Ray Dalio Bridgewater Associates	145.2K	$2M	0.0%	Trim−484
10	AQR Capital Management	97.5K	$2M	0.0%	Added+49.5K
11	Paul Tudor Jones Tudor Investment	89.4K	$1M	0.0%	New+34.7K
12	Mario Gabelli GAMCO	44.5K	$722K	0.0%	Trim−12.0K
13	Paul Tudor Jones Tudor Investment	34.7K	$563K	0.0%	New+34.7K
14	Izzy Englander Millennium Mgmt	23.7K	$385K	0.0%	Trim−652.6K
15	Steve Cohen Point72	23.5K	$381K	0.0%	Sold−305.3K
16	Izzy Englander Millennium Mgmt	17.8K	$289K	0.0%	Trim−652.6K

Recent moves

20 transactions

ADDAQR Capital Management
+49,464 · 2025Q4
TRIMIzzy Englander (Millennium Mgmt)
−652,605 · 2025Q4
TRIMT. Rowe Price
−1,836,010 · 2025Q4
ADDTwo Sigma Investments
+62,981 · 2025Q4
SOLDSteve Cohen (Point72)
−305,316 · 2025Q4
SOLDD.E. Shaw & Co.
−211,433 · 2025Q4
NEWPaul Tudor Jones (Tudor Investment)
+34,674 · 2025Q4
ADDWellington Management
+3,484,689 · 2025Q4
ADDKen Griffin (Citadel Advisors)
+374,757 · 2025Q4
TRIMRay Dalio (Bridgewater Associates)
−484 · 2025Q4
TRIMMario Gabelli (GAMCO)
−11,990 · 2025Q4
TRIMFirst Eagle Investment Management
−279,000 · 2025Q4
NEWSteve Cohen (Point72)
+305,316 · 2025Q3
ADDTwo Sigma Investments
+62,605 · 2025Q3
NEWIzzy Englander (Millennium Mgmt)
+676,349 · 2025Q3
ADDD.E. Shaw & Co.
+179,486 · 2025Q3
ADDT. Rowe Price
+2,429,904 · 2025Q3
TRIMWellington Management
−303,288 · 2025Q3
ADDAQR Capital Management
+27,111 · 2025Q3
SOLDNorges Bank (Norway SWF)
−108,716 · 2025Q3

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