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
Q2 		$273M Sell
1,263,429
-436,649
-26% -$83.5M 0.24% 137
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

Fidelity Investments
Fidelity Investments Boston, Massachusetts $2.3T AUM 54.33% 1-Year Est. Return
BlackRock
BlackRock New York $6.73T AUM 46.02% 1-Year Est. Return
Primecap Management
Primecap Management Pasadena, California $169B AUM 114.72% 1-Year Est. Return
Vanguard Capital Management
Vanguard Capital Management Malvern, Pennsylvania $4.68T AUM
State Street
State Street Boston, Massachusetts $3.37T AUM 44.26% 1-Year Est. Return
Vanguard Portfolio Management
Vanguard Portfolio Management Malvern, Pennsylvania $2.22T AUM
Geode Capital Management
Geode Capital Management Boston, Massachusetts $1.88T AUM 44.46% 1-Year Est. Return
Wellington Management Group
Wellington Management Group Boston, Massachusetts $580B AUM 38.23% 1-Year Est. Return
Norges Bank
Norges Bank Oslo, Norway $1T AUM
Morgan Stanley
Morgan Stanley New York $1.89T AUM 35.08% 1-Year Est. Return

Boston Partners's BIIB Position: Q2 2026 in Review

Boston Partners reduced its Biogen (BIIB) stake by 26% in Q2 2026, selling an estimated $83.5M and leaving 1,263,429 shares worth $273M. The position accounts for 0.24% of the portfolio, ranked #137.

Boston Partners first reported a position in BIIB in Q2 2018 and has held it in 18 quarters since. The position peaked at $416M in Q4 2019. 1,043 funds tracked by Wall St. Rank hold BIIB as of Q2 2026.

  • Boston Partners held 1,263,429 shares of Biogen worth $273M as of Q2 2026.
  • Boston Partners sold 436,649 Biogen shares in Q2 2026, an estimated $83.5M.
  • Biogen made up 0.24% of Boston Partners's portfolio in Q2 2026, its #137 holding.
  • Boston Partners first reported a position in Biogen in Q2 2018 and has held it in 18 quarters since.
  • Boston Partners's Biogen position peaked at $416M in Q4 2019.
  • 1,043 funds tracked by Wall St. Rank held Biogen as of Q2 2026.

Based on Boston Partners's 13F filing for Q2 2026, filed 4 Aug 2026.