Alyeska Investment Group
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Alyeska Investment Group’s Biogen BIIB Stock Holding History

Alyeska Investment Group’s Portfolio BIIB Stock Details BIIB Fund Activity
Bought
Maintained
Sold
Quarter Market Value Status Shares Change in
Stake 		Trade Value Portfolio Weight Portfolio Position
2026
Q1 		$148M Sell
805,050
-219,218
-21% -$40.4M 0.42% 53
2025
Q4 		$180M Buy
1,024,268
+178,991
+21% +$29.2M 0.51% 35
2025
Q3 		$118M Buy
845,277
+336,504
+66% +$45.5M 0.36% 69
2025
Q2 		$63.9M Buy
+508,773
New +$63.4M 0.23% 129
2024
Q3 		– Sell
-401,005
Closed -$93M – 540
2024
Q2 		$93M Buy
401,005
+234,312
+141% +$50.9M 0.53% 50
2024
Q1 		$35.9M Sell
166,693
-255,987
-61% -$60M 0.22% 153
2023
Q4 		$109M Sell
422,680
-19,396
-4% -$4.76M 0.72% 33
2023
Q3 		$114M Buy
442,076
+74,808
+20% +$20M 0.77% 25
2023
Q2 		$105M Buy
+367,268
New +$109M 0.78% 23
2023
Q1 		– Sell
-25,064
Closed -$6.94M – 455
2022
Q4 		$6.94M Buy
+25,064
New +$7.08M 0.07% 236
2021
Q3 		– Sell
-65,367
Closed -$22.6M – 688
2021
Q2 		$22.6M Buy
+65,367
New +$19.8M 0.26% 114
2017
Q3 		– Sell
-149,507
Closed -$40.6M – 469
2017
Q2 		$40.6M Buy
+149,507
New +$39.5M 0.34% 106
2016
Q4 		– Sell
-149,217
Closed -$46.7M – 478
2016
Q3 		$46.7M Buy
+149,217
New +$44.2M 0.43% 69
2016
Q2 		– Sell
-23,381
Closed -$6.09M – 427
2016
Q1 		$6.09M Buy
23,381
+17,546
+301% +$4.63M 0.06% 272
2015
Q4 		$1.79M Buy
+5,835
New +$1.68M 0.02% 310
2015
Q3 		– Sell
-7,500
Closed -$3.03M – 468
2015
Q2 		$3.03M Buy
+7,500
New +$3.01M 0.03% 313
2013
Q3 		– Sell
-35,000
Closed -$7.53M – 305
2013
Q2 		$7.53M Buy
+35,000
New +$7.48M 0.37% 85

Other funds holding BIIB

BlackRock
BlackRock New York $5.72T AUM 30.48% 1-Year Est. Return
Primecap Management
Primecap Management Pasadena, California $127B AUM 44.11% 1-Year Est. Return
Fidelity Investments
Fidelity Investments Boston, Massachusetts $1.9T AUM 41.92% 1-Year Est. Return
VCM
Vanguard Capital Management Malvern, Pennsylvania $4.04T AUM
State Street
State Street Boston, Massachusetts $2.9T AUM 29.55% 1-Year Est. Return
VPM
Vanguard Portfolio Management Malvern, Pennsylvania $1.91T AUM
Geode Capital Management
Geode Capital Management Boston, Massachusetts $1.61T AUM 30.72% 1-Year Est. Return
Wellington Management Group
Wellington Management Group Boston, Massachusetts $535B AUM 26.23% 1-Year Est. Return
Morgan Stanley
Morgan Stanley New York $1.66T AUM 25.57% 1-Year Est. Return
JP Morgan Chase
JP Morgan Chase New York $1.56T AUM 27.86% 1-Year Est. Return

Alyeska Investment Group's BIIB Position: Q1 2026 in Review

Alyeska Investment Group reduced its Biogen (BIIB) stake by 21% in Q1 2026, selling an estimated $40.4M and leaving 805,050 shares worth $148M. The position accounts for 0.42% of the portfolio, ranked #53.

Alyeska Investment Group first reported a position in BIIB in Q2 2013 and has held it in 17 quarters since. The position peaked at $180M in Q4 2025. 1,002 funds tracked by Wall St. Rank hold BIIB as of Q1 2026.

  • Alyeska Investment Group held 805,050 shares of Biogen worth $148M as of Q1 2026.
  • Alyeska Investment Group sold 219,218 Biogen shares in Q1 2026, an estimated $40.4M.
  • Biogen made up 0.42% of Alyeska Investment Group's portfolio in Q1 2026, its #53 holding.
  • Alyeska Investment Group first reported a position in Biogen in Q2 2013 and has held it in 17 quarters since.
  • Alyeska Investment Group's Biogen position peaked at $180M in Q4 2025.
  • 1,002 funds tracked by Wall St. Rank held Biogen as of Q1 2026.

Based on Alyeska Investment Group's 13F filing for Q1 2026, filed 15 May 2026.