Question 1

Does Vanguard Group own BIIB stock?

Accepted Answer

As of its last 13F, for Q4 2025, Vanguard Group held 17,447,092 shares of BIIB (Biogen), worth $3.1B.

Question 2

How many shares of BIIB does Vanguard Group own?

Accepted Answer

As of its last 13F, for Q4 2025, Vanguard Group held 17,447,092 shares of BIIB (Biogen).

Question 3

What is Vanguard Group's BIIB position worth?

Accepted Answer

As of its last 13F, for Q4 2025, Vanguard Group's BIIB position was worth $3.1B.

Question 4

Is Vanguard Group buying or selling BIIB?

Accepted Answer

In Q4 2025, Vanguard Group increased its BIIB position by 157,857 shares (+0.9%).

Question 5

When did Vanguard Group first buy BIIB?

Accepted Answer

Vanguard Group already held BIIB in its Q3 2024 13F, the earliest on record, and listed it in 6 quarterly 13F filings.

Quarter	Action	Shares	Change	Value	Weight	Price	Conviction
2025-Q4 Latest	Increased	17.4M	+0.9%	$3.1B	0.0%	$175.99	32
2025-Q3	Decreased	17.3M	-0.0%	$2.4B	0.0%	$140.08	0
2025-Q2	Increased	17.3M	+1.5%	$2.2B	0.0%	$125.59	32
2025-Q1	Increased	17M	+1.7%	$2.3B	0.0%	$136.84	32
2024-Q4	Increased	16.7M	+0.4%	$2.6B	0.0%	$152.92	32
2024-Q3	First report	16.7M	-	$3.2B	0.1%	$193.84	0

BIIB6 quarters

BIIB
6 quarters