BIOGEN INC (BIIB) Stock Institutional Trading Activity


BIOGEN INC (BIIB) position changes reported by tracked institutional filers across multiple SEC 13F reporting periods. Based on recent SEC 13F filings (Q4 2025), investors with some of the largest reported share count changes include Renaissance Technologies LLC, Causeway Capital Management, Sequoia Financial Advisors, Hillman Value Fund, and Parnassus Endeavor Fund. Explore insights into buying and selling patterns, position changes, and investment conviction levels to understand institutional trading behavior and market dynamics.

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Portfolio quarterNameTypeQuantityRemainingReported stock balance
Q3 2016First Eagle U.S. ValueBuy124,500457,260$143,136
Q3 2016Viking Global InvestorsSell-1,024,1712,186,336$684,389
Q2 2016Muhlenkamp & CoSell-15023,703$5,732
Q2 2016Renaissance Technologies LLCSell-87,26140,400$9,770
Q2 2016First Eagle U.S. ValueBuy108,175332,760$80,468
Q2 2016Causeway Capital ManagementBuy489,263489,263$135,200
Q2 2016Viking Global InvestorsBuy2,979,5603,210,507$776,365
Q1 2016Muhlenkamp & CoBuy23,85323,853$6,209
Q1 2016Mairs & Power Growth FundSell-701,025$267
Q1 2016Renaissance Technologies LLCBuy92,700127,661$33,233
Q1 2016First Eagle U.S. ValueBuy30,700224,585$58,464
Q1 2016Viking Global InvestorsSell-137,917230,947$60,120
Q4 2015Vulcan Value PartnersBuy750750$230
Q4 2015First Eagle U.S. ValueBuy193,885193,885$59,397
Q4 2015Viking Global InvestorsSell-144,580368,864$113,001
Q3 2015Renaissance Technologies LLCSell-70,30034,961$10,202
Q2 2015Mairs & Power Growth FundSell-251,095$442
Q2 2015Renaissance Technologies LLCBuy74,961105,261$42,519
Q2 2015Viking Global InvestorsBuy124,544513,444$207,401
Q2 2015Eagle Capital ManagementSell-228,542$3,450
Q1 2015Mairs & Power Growth FundSell-201,120$473
Q1 2015Renaissance Technologies LLCSell-34,86130,300$12,794
Q1 2015Eagle Capital ManagementSell-428,564$3,616
Q4 2014Mairs & Power Growth FundSell-301,140$387
Q4 2014Renaissance Technologies LLCSell-27,50065,161$22,119
Q4 2014Eagle Capital ManagementBuy528,606$2,921
Q3 2014Mairs & Power Growth FundBuy451,170$387
Q3 2014Renaissance Technologies LLCSell-36,60092,661$30,653
Q3 2014Eagle Capital ManagementSell-1838,554$2,830
Q2 2014Renaissance Technologies LLCSell-413,077129,261$40,757

Frequently asked questions about BIIB activity

  • Which institutional owners are buying BIIB?

    Institutional owners buying BIIB include investors who have either initiated new positions or increased their existing holdings based on recent SEC 13F filings. The activity table above highlights which funds added shares in the latest reporting periods and how their positions changed over time.

  • What does "buy" mean in BIIB activity?

    "Buy" means an investor increased their reported position in BIIB compared to the prior reporting period. This reflects growing exposure to BIOGEN INC (BIIB) rather than necessarily a brand-new position (though new positions also appear as buys when prior quantity was zero).

  • Is institutional interest in BIIB increasing?

    Institutional interest in BIIB can be assessed by comparing the number of tracked funds adding or increasing positions versus those trimming or exiting across the periods shown. A higher number of additions typically signals increasing participation among large filers, but it should be read alongside position sizes and the full table.