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Magnetar Financial’s White Mountains Insurance WTM Stock Holding History

Magnetar Financial’s Portfolio WTM Stock Details WTM Fund Activity
Bought
Maintained
Sold
Quarter Market Value Status Shares Change in
Stake 		Trade Value Portfolio Weight Portfolio Position
2025
Q4 		– Sell
-881
Closed -$1.47M – 1245
2025
Q3 		$1.47M Buy
+881
New +$1.57M 0.01% 407
2025
Q2 		– Sell
-118
Closed -$227K – 1180
2025
Q1 		$227K Buy
+118
New +$222K ﹤0.01% 642
2018
Q2 		– Sell
-559
Closed -$460K – 707
2018
Q1 		$460K Sell
559
-1,127
-67% -$930K 0.01% 356
2017
Q4 		$1.44M Buy
+1,686
New +$1.47M 0.03% 160
2017
Q3 		– Sell
-647
Closed -$562K – 936
2017
Q2 		$562K Sell
647
-69
-10% -$59.9K 0.01% 480
2017
Q1 		$630K Buy
+716
New +$641K 0.01% 425

Other funds holding WTM

Vanguard Group
Vanguard Group Malvern, Pennsylvania $6.9T AUM 27.45% 1-Year Est. Return
Dimensional Fund Advisors
Dimensional Fund Advisors Austin, Texas $552B AUM 44.19% 1-Year Est. Return
Neuberger Berman Group
Neuberger Berman Group New York $150B AUM 40.08% 1-Year Est. Return
RRAM
River Road Asset Management Louisville, Kentucky $8.99B AUM 12.83% 1-Year Est. Return
BlackRock
BlackRock New York $6.73T AUM 46.02% 1-Year Est. Return
Fuller & Thaler Asset Management
Fuller & Thaler Asset Management San Mateo, California $36.7B AUM 74.15% 1-Year Est. Return
CB
Cooke & Bieler Philadelphia, Pennsylvania $8.65B AUM 9.66% 1-Year Est. Return
FMI
Fiduciary Management Inc Milwaukee, Wisconsin $7.03B AUM 11.68% 1-Year Est. Return
Morgan Stanley
Morgan Stanley New York $1.89T AUM 35.08% 1-Year Est. Return
WCM
Wallace Capital Management Dallas, Texas $912M AUM 21.45% 1-Year Est. Return

Magnetar Financial's WTM Position: Q4 2025 in Review

Magnetar Financial sold out of White Mountains Insurance (WTM) in Q4 2025, closing a stake of 881 shares — an estimated $1.47M sold.

Magnetar Financial first reported a position in WTM in Q1 2017 and held it in 6 quarters. The position peaked at $1.47M in Q3 2025. 352 funds tracked by Wall St. Rank hold WTM as of Q4 2025.

  • Magnetar Financial reported no remaining White Mountains Insurance position as of Q4 2025 after selling out during the quarter.
  • Magnetar Financial sold 881 White Mountains Insurance shares in Q4 2025, an estimated $1.47M.
  • Magnetar Financial first reported a position in White Mountains Insurance in Q1 2017 and held it in 6 quarters.
  • Magnetar Financial's White Mountains Insurance position peaked at $1.47M in Q3 2025.
  • 352 funds tracked by Wall St. Rank held White Mountains Insurance as of Q4 2025.

Based on Magnetar Financial's 13F filing for Q4 2025, filed 17 Feb 2026.