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Biogen Inc.· BIIB

🇺🇸 US · LargeSP500NASDAQ

Healthcare Drug Manufacturers - General Website

Price: $249.01
Day: -1.82%
Mkt Cap: $36.81B
52W Range: $148.51 – $258.78
Volume: 1.17M
Beta: 0.17

D55D FrameworkQuarterly Data

Holdings Analysis

Insider activity, institutional flows, and fund ownership.

Holdings sentiment: 3.8 / 5 (Bullish), from 3 of 3 components
Institutions Q2 2026: 1,099 institutions hold; 552 added, 304 reduced

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Holdings Sentiment

BIIB Holdings Sentiment Score

A weighted 1-5 sentiment score across insider, institutional, and fund activity.

Holdings Sentiment

3.8/5

Bullish

Weighted across 3 components

Component Breakdown (3 of 3 available)

Insider Activity

40% weight

Institutional Flow

50% weight

+66

Fund Flow

10% weight

+25

Overall Holdings sentiment of 3.8/5 (Bullish) based on a weighted combination of 3 components. Insider activity uses a relative-baseline comparison against the stock's own history; institutional flow tracks position momentum and 13F share changes; fund flow measures ETF / mutual-fund buying vs selling. Higher scores mean holder activity reads more positive: more buying, or less selling than the stock's usual pace.Last updated November 2, 2026.

Insider Trading Activity

Insider trading analysis comparing the latest quarter against the stock's own historical baseline.

Insider Activity for BIIB

Each quarter's selling vs the stock's own trailing 6-quarter average; 1.0x is typical for this stock.

Neutral

Routine insider selling in Q3 2026

2 sales totaling $239.7K (1.2K shares)

Share volume is below the historical pace (0.4x average)

All sales came from a single insider

Buying seen in 3 of 15 quarters

0.4x

Selling pace

vs own 6-qtr average

Light

0.14%

Stake sold

of active insiders' holdings

1 seller

Seller breadth

vs 0.8 avg per quarter

Q1 2026

Last insider purchase

buying in 3 of 16 quarters

Notable Recent Transactions, BIIB

Top 8 highest-value insider trades from the last 8 quarters

SHERWIN STEPHEN A

Director

Sell

8,760 shares at $150.02

≈43.6% of their stake at the time

Mar 7, 2025$1.31M

Singhal Priya

Head of Development

Sell

2,660 shares at $199.83

≈24.9% of their stake at the time

Feb 9, 2026$531.55K

Singhal Priya

Head of Development

Sell

3,806 shares at $126.25

≈41.2% of their stake at the time

May 19, 2025$480.51K

Izzar Rachid

Head of Global Product Strat.

Sell

2,223 shares at $135.00

≈26.0% of their stake at the time

Jul 8, 2025$300.11K

DORSA CAROLINE

Director

Buy

1,235 shares at $122.72

≈4.4% of their stake after buying

May 2, 2025$151.56K

Singhal Priya

Head of Development

Sell

748 shares at $179.30

≈10.7% of their stake at the time

Feb 2, 2026$134.12K

Minor Lloyd

Director

Sell

593 shares at $203.34

≈15.3% of their stake at the time

Aug 3, 2026$120.58K

Minor Lloyd

Director

Sell

593 shares at $200.96

≈18.1% of their stake at the time

Aug 4, 2026$119.17K

Institutional Ownership Analysis

Institutional ownership analysis with position momentum, 13F share flow, and ownership percentage trends.

Institutional Positions for BIIB

Institutions adding (new + increased) above zero, reducing (reduced + closed) below, net as a line

New Increased Reduced Closed Net (adding − reducing)

Very Bullish

Institutions accumulating in Q2 2026

96.4% institutional ownership

Moderate accumulation: 677 adding vs 397 reducing

13F shares increased by 3.3%, a notable change

+280

Net breadth

677 adding vs 397 reducing

Accumulating

1.71

Add / reduce ratio

in Q2 2026

+32

New − closed

125 initiated, 93 exited

8 of 9

Top holders adding

largest holders with a known change

Position Changes

Q2 2026: how are institutions adjusting their positions?

+677 growing-397 shrinkingNet: +280

125

552

304

New (125)

Increased (552)

Reduced (304)

Closed (93)

Top Institutional Holders, BIIB

Largest 8 institutional positions by ownership percentage as of Q2 2026

FMR LLC

18.2M

$3.9B

Ownership

12.33%

+41.8%

BLACKROCK, INC.

16.0M

$3.5B

Ownership

10.82%

-0.3%

PRIMECAP MANAGEMENT CO/CA/

15.2M

$3.3B

Ownership

10.26%

+2.3%

VANGUARD CAPITAL MANAGEMENT LLC

9.7M

$2.1B

Ownership

6.53%

+0.8%

STATE STREET CORP

7.3M

$1.6B

Ownership

4.99%

+2.5%

VANGUARD PORTFOLIO MANAGEMENT LLC

6.6M

$1.4B

Ownership

4.47%

+0.8%

GEODE CAPITAL MANAGEMENT, LLC

4.4M

$957.9M

Ownership

3.01%

+2.1%

WELLINGTON MANAGEMENT GROUP LLP

3.1M

$673.6M

Ownership

2.11%

+4.9%

ETF and Mutual Fund Holdings

ETF and mutual fund activity breakdown showing buying vs selling funds, top fund holders, and detailed holdings.

Fund Activity

Q3 2026: 134 ETFs and mutual funds reporting

71 buying45 sellingNet: +26

Buying (71)

Unchanged (18)

Selling (45)

In total, funds bought 3.2M shares and sold 6.5M this quarter. Each fund counts once in the bar above, whatever the size of its move.

Bullish

Funds accumulating in Q3 2026

134 ETFs and mutual funds reporting

71 funds buying vs 45 selling

Top Fund Holders, BIIB

Largest 8 ETF and mutual fund positions by shares held, each fund's latest filing

Fidelity Rutland Square Trust II

1.8M

Weight

5.39%

Aug 31, 2026Decreased

BLACKROCK FUNDS

366.5K

Weight

9.69%

Aug 31, 2026Increased

iSHARES TRUST

117.2K

Weight

0.14%

Aug 31, 2026Decreased

ADAMS DIVERSIFIED EQUITY FUND, INC.

97.1K

Weight

66.02%

Sep 30, 2026Decreased

TRUST FOR PROFESSIONAL MANAGERS

56.8K

Weight

4.79%

Aug 31, 2026Decreased

DBX ETF TRUST

31.3K

Weight

1.96%

Aug 31, 2026Increased

iShares, Inc.

31.0K

Weight

0.18%

Aug 31, 2026Increased

Tidal Trust I

16.9K

Weight

5.82%

Aug 31, 2026Increased

Biogen Inc.· BIIB

Holdings Analysis

Insider Trading Activity

1.3Transaction History36Real market purchases and sales onlyShow All Types

Institutional Ownership Analysis

2.4Detailed Holdings47Most recent institutional positions with changes and valuations

ETF and Mutual Fund Holdings

3.3Fund Holdings Details25Most recent ETF and mutual fund holdings with share counts and weights

Search stocks

Holdings Analysis

Insider Trading Activity

1.3Transaction History36Real market purchases and sales onlyShow All Types

Institutional Ownership Analysis

2.4Detailed Holdings47Most recent institutional positions with changes and valuations

ETF and Mutual Fund Holdings

3.3Fund Holdings Details25Most recent ETF and mutual fund holdings with share counts and weights