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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
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

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

Portolan Capital Management's BIIB Position: Q1 2026 in Review

Portolan Capital Management increased its Biogen (BIIB) stake by 39% in Q1 2026, buying an estimated $6.17M and bringing the position to 118,481 shares worth $21.7M. The position accounts for 1.16% of the portfolio, ranked #26.

Portolan Capital Management first reported a position in BIIB in Q4 2025 and has held it in 2 quarters since. 1,002 funds tracked by Wall St. Rank hold BIIB as of Q1 2026.

  • Portolan Capital Management held 118,481 shares of Biogen worth $21.7M as of Q1 2026.
  • Portolan Capital Management bought 33,491 Biogen shares in Q1 2026, an estimated $6.17M.
  • Biogen made up 1.16% of Portolan Capital Management's portfolio in Q1 2026, its #26 holding.
  • Portolan Capital Management first reported a position in Biogen in Q4 2025 and has held it in 2 quarters since.
  • 1,002 funds tracked by Wall St. Rank held Biogen as of Q1 2026.

Based on Portolan Capital Management's 13F filing for Q1 2026, filed 15 May 2026.