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Portolan Capital Management’s Biogen BIIB Stock Holding History

Portolan Capital Management’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 		$30.9M Buy
142,856
+24,375
+21% +$4.66M 1.16% 24
2026
Q1 		$21.7M Buy
118,481
+33,491
+39% +$6.17M 1.16% 26
2025
Q4 		$15M Buy
+84,990
New +$13.9M 0.8% 40

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

Portolan Capital Management's BIIB Position: Q2 2026 in Review

Portolan Capital Management increased its Biogen (BIIB) stake by 21% in Q2 2026, buying an estimated $4.66M and bringing the position to 142,856 shares worth $30.9M. The position accounts for 1.16% of the portfolio, ranked #24.

Portolan Capital Management first reported a position in BIIB in Q4 2025 and has held it in 3 quarters since. 1,043 funds tracked by Wall St. Rank hold BIIB as of Q2 2026.

  • Portolan Capital Management held 142,856 shares of Biogen worth $30.9M as of Q2 2026.
  • Portolan Capital Management bought 24,375 Biogen shares in Q2 2026, an estimated $4.66M.
  • Biogen made up 1.16% of Portolan Capital Management's portfolio in Q2 2026, its #24 holding.
  • Portolan Capital Management first reported a position in Biogen in Q4 2025 and has held it in 3 quarters since.
  • 1,043 funds tracked by Wall St. Rank held Biogen as of Q2 2026.

Based on Portolan Capital Management's 13F filing for Q2 2026, filed 14 Aug 2026.