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Castleark Management’s Magnite MGNI Stock Holding History

Castleark Management’s Portfolio MGNI Stock Details MGNI Fund Activity
Bought
Maintained
Sold
Quarter Market Value Status Shares Change in
Stake 		Trade Value Portfolio Weight Portfolio Position
2025
Q4 		– Sell
-193,185
Closed -$4.21M – 320
2025
Q3 		$4.21M Buy
193,185
+50,035
+35% +$1.18M 0.12% 157
2025
Q2 		$3.45M Buy
+143,150
New +$2.11M 0.1% 149
2023
Q3 		– Sell
-409,820
Closed -$5.59M – 302
2023
Q2 		$5.59M Buy
409,820
+132,040
+48% +$1.47M 0.25% 93
2023
Q1 		$2.57M Buy
277,780
+91,030
+49% +$970K 0.13% 151
2022
Q4 		$1.98M Buy
+186,750
New +$1.7M 0.1% 167
2021
Q2 		– Sell
-245,191
Closed -$10.2M – 347
2021
Q1 		$10.2M Buy
+245,191
New +$10.6M 0.37% 83
2016
Q2 		– Sell
-321,035
Closed -$5.87M – 387
2016
Q1 		$5.87M Buy
+321,035
New +$4.92M 0.18% 148
2015
Q3 		– Sell
-253,055
Closed -$3.79M – 388
2015
Q2 		$3.79M Buy
+253,055
New +$4.36M 0.1% 225

Other funds holding MGNI

Vanguard Group
Vanguard Group Malvern, Pennsylvania $6.9T AUM 27.45% 1-Year Est. Return
Capital Research Global Investors
Capital Research Global Investors Los Angeles, California $645B AUM 30.41% 1-Year Est. Return
BlackRock
BlackRock New York $5.72T AUM 30.48% 1-Year Est. Return
Wellington Management Group
Wellington Management Group Boston, Massachusetts $535B AUM 26.23% 1-Year Est. Return
Fidelity Investments
Fidelity Investments Boston, Massachusetts $1.9T AUM 41.92% 1-Year Est. Return
American Century Companies
American Century Companies Kansas City, Missouri $194B AUM 35% 1-Year Est. Return
Boston Partners
Boston Partners Boston, Massachusetts $95.5B AUM 28.4% 1-Year Est. Return
Dimensional Fund Advisors
Dimensional Fund Advisors Austin, Texas $481B AUM 30.42% 1-Year Est. Return
N
Nuveen Charlotte, North Carolina $369B AUM 31.66% 1-Year Est. Return
Geode Capital Management
Geode Capital Management Boston, Massachusetts $1.61T AUM 30.72% 1-Year Est. Return

Castleark Management's MGNI Position: Q4 2025 in Review

Castleark Management sold out of Magnite (MGNI) in Q4 2025, closing a stake of 193,185 shares — an estimated $4.21M sold.

Castleark Management first reported a position in MGNI in Q2 2015 and held it in 8 quarters. The position peaked at $10.2M in Q1 2021. 304 funds tracked by Wall St. Rank hold MGNI as of Q4 2025.

  • Castleark Management reported no remaining Magnite position as of Q4 2025 after selling out during the quarter.
  • Castleark Management sold 193,185 Magnite shares in Q4 2025, an estimated $4.21M.
  • Castleark Management first reported a position in Magnite in Q2 2015 and held it in 8 quarters.
  • Castleark Management's Magnite position peaked at $10.2M in Q1 2021.
  • 304 funds tracked by Wall St. Rank held Magnite as of Q4 2025.

Based on Castleark Management's 13F filing for Q4 2025, filed 13 Feb 2026.