Dmitry Balyasny’s Biogen BIIB Stock Holding History

Dmitry Balyasny’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	–	Sell	-39,900	Closed	-$7.02M	–	2911
2025 Q4	$7.02M	Buy	39,900 +38,300	+2,394%	+$6.26M	0.01%	1212
2025 Q3	$224K	Buy	+1,600	New	+$216K	﹤0.01%	2692
2024 Q4	–	Sell	-6,400	Closed	-$1.24M	–	2746
2024 Q3	$1.24M	Buy	+6,400	New	+$1.34M	﹤0.01%	1875
2020 Q2	–	Sell	-90,000	Closed	-$28.5M	–	1135
2020 Q1	$28.5M	Buy	+90,000	New	+$27.3M	0.34%	69
2018 Q4	–	Sell	-57,000	Closed	-$19.3M	–	1409
2018 Q3	$19.3M	Buy	+57,000	New	+$19.6M	0.09%	309
2017 Q1	–	Sell	-90,000	Closed	-$23.5M	–	1589
2016 Q4	$23.5M	Buy	+90,000	New	+$26.7M	0.13%	227
2016 Q1	–	Sell	-25,000	Closed	-$7.66M	–	1276
2015 Q4	$7.66M	Buy	+25,000	New	+$7.18M	0.05%	417
2015 Q1	–	Sell	-29,600	Closed	-$10M	–	944
2014 Q4	$10M	Buy	+29,600	New	+$9.58M	0.09%	297

Other funds holding BIIB

Fidelity Investments Boston, Massachusetts $2.3T AUM 54.33% 1-Year Est. Return

BlackRock New York $6.73T AUM 46.02% 1-Year Est. Return

Primecap Management Pasadena, California $169B AUM 114.72% 1-Year Est. Return

Vanguard Capital Management Malvern, Pennsylvania $4.68T AUM

State Street Boston, Massachusetts $3.37T AUM 44.26% 1-Year Est. Return

Vanguard Portfolio Management Malvern, Pennsylvania $2.22T AUM

Geode Capital Management Boston, Massachusetts $1.88T AUM 44.46% 1-Year Est. Return

Wellington Management Group Boston, Massachusetts $580B AUM 38.23% 1-Year Est. Return

Norges Bank Oslo, Norway $1T AUM

Morgan Stanley New York $1.89T AUM 35.08% 1-Year Est. Return

Dmitry Balyasny's BIIB Position: Q2 2026 in Review

Dmitry Balyasny reduced its Biogen (BIIB) stake by 59% in Q2 2026, selling an estimated $73.6M and leaving 265,090 shares worth $57.3M. The position accounts for 0.07% of the portfolio, ranked #323.

Dmitry Balyasny first reported a position in BIIB in Q4 2014 and has held it in 43 quarters since. The position peaked at $174M in Q4 2017. 1,036 funds tracked by Wall St. Rank hold BIIB as of Q2 2026.

Dmitry Balyasny held 265,090 shares of Biogen worth $57.3M as of Q2 2026.
Dmitry Balyasny sold 384,956 Biogen shares in Q2 2026, an estimated $73.6M.
Biogen made up 0.07% of Dmitry Balyasny's portfolio in Q2 2026, its #323 holding.
Dmitry Balyasny first reported a position in Biogen in Q4 2014 and has held it in 43 quarters since.
Dmitry Balyasny's Biogen position peaked at $174M in Q4 2017.
1,036 funds tracked by Wall St. Rank held Biogen as of Q2 2026.

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