Boston Partners
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Boston Partners’s Biogen BIIB Stock Holding History

Boston Partners’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 		$312M Sell
1,700,078
-20,517
-1% -$3.78M 0.33% 100
2025
Q4 		$303M Buy
+1,720,595
New +$281M 0.31% 108
2022
Q1 		– Sell
-313,782
Closed -$75.3M – 703
2021
Q4 		$75.3M Sell
313,782
-18,807
-6% -$4.84M 0.09% 216
2021
Q3 		$94.1M Buy
332,589
+11,506
+4% +$3.77M 0.12% 208
2021
Q2 		$111M Buy
321,083
+15,047
+5% +$4.56M 0.14% 196
2021
Q1 		$85.6M Buy
306,036
+13,221
+5% +$3.57M 0.11% 214
2020
Q4 		$71.7M Buy
292,815
+950
+0.3% +$245K 0.11% 210
2020
Q3 		$82.8M Sell
291,865
-12,909
-4% -$3.6M 0.15% 183
2020
Q2 		$81.5M Sell
304,774
-34,640
-10% -$10.4M 0.15% 181
2020
Q1 		$107M Sell
339,414
-1,061,842
-76% -$322M 0.21% 138
2019
Q4 		$416M Sell
1,401,256
-111,192
-7% -$30.9M 0.55% 59
2019
Q3 		$353M Sell
1,512,448
-57,411
-4% -$13.4M 0.48% 64
2019
Q2 		$367M Buy
1,569,859
+647,141
+70% +$149M 0.48% 70
2019
Q1 		$218M Buy
922,718
+746,711
+424% +$235M 0.29% 102
2018
Q4 		$53M Buy
176,007
+3,920
+2% +$1.25M 0.08% 230
2018
Q3 		$60.8M Sell
172,087
-90,040
-34% -$31M 0.07% 227
2018
Q2 		$76.1M Buy
+262,127
New +$73.7M 0.09% 205

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

Boston Partners's BIIB Position: Q1 2026 in Review

Boston Partners reduced its Biogen (BIIB) stake by 1.2% in Q1 2026, selling an estimated $3.78M and leaving 1,700,078 shares worth $312M. The position accounts for 0.33% of the portfolio, ranked #100.

Boston Partners first reported a position in BIIB in Q2 2018 and has held it in 17 quarters since. The position peaked at $416M in Q4 2019. 1,002 funds tracked by Wall St. Rank hold BIIB as of Q1 2026.

  • Boston Partners held 1,700,078 shares of Biogen worth $312M as of Q1 2026.
  • Boston Partners sold 20,517 Biogen shares in Q1 2026, an estimated $3.78M.
  • Biogen made up 0.33% of Boston Partners's portfolio in Q1 2026, its #100 holding.
  • Boston Partners first reported a position in Biogen in Q2 2018 and has held it in 17 quarters since.
  • Boston Partners's Biogen position peaked at $416M in Q4 2019.
  • 1,002 funds tracked by Wall St. Rank held Biogen as of Q1 2026.

Based on Boston Partners's 13F filing for Q1 2026, filed 11 May 2026.