CSS LLC’s Biogen BIIB Stock Holding History

CSS LLC’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
2022 Q4	–	Sell	-31,000	Closed	-$8.28M	–	959
2022 Q3	$8.28M	Buy	+31,000	New	+$6.58M	0.39%	47
2022 Q1	–	Sell	-11,000	Closed	-$2.64M	–	1171
2021 Q4	$2.64M	Buy	11,000 +8,700	+378%	+$2.24M	0.09%	196
2021 Q3	$651K	Sell	2,300 -9,200	-80%	-$3.02M	0.03%	554
2021 Q2	$3.98M	Buy	+11,500	New	+$3.48M	0.16%	120
2021 Q1	–	Sell	-25,800	Closed	-$6.32M	–	935
2020 Q4	$6.32M	Buy	25,800 +1,800	+8%	+$464K	0.24%	71
2020 Q3	$6.81M	Sell	24,000 -10,000	-29%	-$2.79M	0.32%	63
2020 Q2	$9.1M	Buy	34,000 +10,000	+42%	+$3.01M	0.52%	41
2020 Q1	$7.59M	Buy	24,000 +21,500	+860%	+$6.52M	0.6%	38
2019 Q4	$742K	Buy	+2,500	New	+$694K	0.04%	294

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

CSS LLC's BIIB Position: Q2 2026 in Review

CSS LLC increased its Biogen (BIIB) stake by 5.9% in Q2 2026, buying an estimated $30.6K and bringing the position to 2,880 shares worth $622K. The position accounts for 0.02% of the portfolio, ranked #491.

CSS LLC first reported a position in BIIB in Q1 2020 and has held it in 13 quarters since. The position peaked at $5.14M in Q2 2020. 1,044 funds tracked by Wall St. Rank hold BIIB as of Q2 2026.

CSS LLC held 2,880 shares of Biogen worth $622K as of Q2 2026.
CSS LLC bought 160 Biogen shares in Q2 2026, an estimated $30.6K.
Biogen made up 0.02% of CSS LLC's portfolio in Q2 2026, its #491 holding.
CSS LLC first reported a position in Biogen in Q1 2020 and has held it in 13 quarters since.
CSS LLC's Biogen position peaked at $5.14M in Q2 2020.
1,044 funds tracked by Wall St. Rank held Biogen as of Q2 2026.

Based on CSS LLC's 13F filing for Q2 2026, filed 14 Aug 2026.