Thomas Steyer’s Biogen BIIB Stock Holding History

Thomas Steyer’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	$15.3M	Buy	+71,000	New	+$13.6M	0.07%	56
2023 Q3	–	Sell	-604,098	Closed	-$172M	–	168
2023 Q2	$172M	Sell	604,098 -15,700	-3%	-$4.67M	0.86%	35
2023 Q1	$172M	Buy	619,798 +27,099	+5%	+$7.5M	0.94%	38
2022 Q4	$164M	Buy	592,699 +287,200	+94%	+$81.1M	0.97%	38
2022 Q3	$81.6M	Buy	305,499 +27,000	+10%	+$5.73M	0.45%	58
2022 Q2	$56.8M	Buy	278,499 +80,700	+41%	+$16.5M	0.31%	69
2022 Q1	$41.7M	Buy	197,799 +50,090	+34%	+$10.9M	0.2%	78
2021 Q4	$35.4M	Sell	147,709 -23,150	-14%	-$5.95M	0.18%	76
2021 Q3	$48.4M	Buy	170,859 +61,859	+57%	+$20.3M	0.23%	77
2021 Q2	$37.7M	Buy	109,000 +6,000	+6%	+$1.82M	0.15%	83
2021 Q1	$28.8M	Hold	103,000	–	–	0.14%	89
2020 Q4	$25.2M	Buy	+103,000	New	+$26.6M	0.15%	85
2018 Q3	–	Sell	-249,000	Closed	-$72.3M	–	103
2018 Q2	$72.3M	Sell	249,000 -91,000	-27%	-$25.6M	0.45%	43
2018 Q1	$93.1M	Sell	340,000 -200,000	-37%	-$62.1M	0.64%	36
2017 Q4	$172M	Buy	540,000 +65,000	+14%	+$20.9M	1.4%	20
2017 Q3	$149M	Buy	475,000 +262,500	+124%	+$77.7M	1.32%	18
2017 Q2	$57.7M	Buy	+212,500	New	+$56.2M	0.6%	34

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

Thomas Steyer's BIIB Position: Q2 2026 in Review

Thomas Steyer opened a new position in Biogen (BIIB) in Q2 2026: 71,000 shares worth $15.3M. The stake represents 0.07% of the portfolio and ranks #56 among its holdings. This is a return to the name: Thomas Steyer previously reported a position in BIIB as recently as Q2 2023.

Thomas Steyer first reported a position in BIIB in Q2 2017 and has held it in 17 quarters since. The position peaked at $172M in Q1 2023. 1,036 funds tracked by Wall St. Rank hold BIIB as of Q2 2026.

Thomas Steyer held 71,000 shares of Biogen worth $15.3M as of Q2 2026.
Biogen was a new Thomas Steyer position in Q2 2026.
Biogen made up 0.07% of Thomas Steyer's portfolio in Q2 2026, its #56 holding.
Thomas Steyer first reported a position in Biogen in Q2 2017 and has held it in 17 quarters since.
Thomas Steyer's Biogen position peaked at $172M in Q1 2023.
1,036 funds tracked by Wall St. Rank held Biogen as of Q2 2026.

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