Comparable stake leader
PRIMECAP MANAGEMENT CO/CA/
SEC ownership of BIOGEN INC.
Top holders, 13D/G large-stake signals, insider positions, and transaction flow tied to CIK 0000875045.
Disclosed value leader
BlackRock, Inc.
Comparable rows
50/50
Latest evidence
01 May 2026
- Public ticker
- BIIB on Nasdaq
- Parsed ownership sources
- 13F, 13D/G, and 3/4/5
- Largest SEC-reported holder
- PRIMECAP MANAGEMENT CO/CA/
- Latest 13D/G holder
- PRIMECAP MANAGEMENT CO/CA/
- Latest parsed ownership date
- 01 May 2026
- Issuer CIK
- 0000875045
- Issuer location
- Cambridge, MA
Ownership snapshot
CIK-linked ownership evidence from parsed SEC filings.
2 signals
Issuer
Names, identifiers, and filing context for this profile.
2 identity fields
Ownership snapshot
Top shareholders of BIOGEN INC. (13F + 13D/G + 3/4/5)
Grouped by holder across the latest SEC ownership disclosures. Start with comparable ownership when available, then verify the linked 13F, 13D/G, or 3/4/5 evidence.
Comparable stake leader
PRIMECAP MANAGEMENT CO/CA/
Disclosed value leader
BlackRock, Inc.
Comparable rows
50/50
Latest evidence
01 May 2026
13F
13D/G
3/4/5
Lead comparable stake: 10%
13D/G row: PRIMECAP MANAGEMENT CO/CA/
Showing 1-8 of 50 holder rows.
Quick read
PRIMECAP MANAGEMENT CO/CA/ leads the comparable SEC ownership view at 10%.
50 of 50 rows have a safely comparable ownership percentage. Use this as a filing-backed starting point, then open the detailed table for source links, reporting role, position value, share count, and filing date.
Open SEC evidence
Opens PRIMECAP MANAGEMENT CO/CA/'s linked filing trail.
Comparable ownership
Top 5
PRIMECAP MANAGEMENT CO/CA/
10%
FMR LLC
8.7%
BlackRock, Inc.
8.5%
VANGUARD CAPITAL MANAGEMENT LLC
7.5%
STATE STREET CORP
5%
Ownership % is shown only when SEC disclosures are safely comparable across share classes.
Detailed SEC evidence table Showing 1-8 of 50 holder rows
| Holder | Evidence | Ownership % | Position | 12M Net Δ | As of |
|---|---|---|---|---|---|
| PRIMECAP MANAGEMENT CO/CA/ |
13F
13D/G
Company
|
10%
from 13D/G
|
$2,705,512,094
14,757,607 shares
|
— | 31 Mar 2026 |
| FMR LLC |
13F
13D/G
Company
|
8.7%
from 13D/G
|
$2,348,006,582
12,807,541 shares
|
— | 31 Mar 2026 |
| BlackRock, Inc. |
13F
13D/G
Company
|
8.5%
from 13D/G
|
$2,928,623,480
15,974,601 shares
|
— | 31 Mar 2026 |
| VANGUARD CAPITAL MANAGEMENT LLC |
13D/G
13F
Vanguard Capital Management · Company
|
7.5%
|
$2,014,716,401
10,989,562 shares
|
$0 | 31 Mar 2026 |
| STATE STREET CORP |
13F
13D/G
Company · STATE STREET CORPORATION
|
5%
from 13D/G
|
$1,314,095,140
7,167,922 shares
|
— | 31 Mar 2026 |
| Caroline Dorsa |
3/4/5
Director
|
0.02%
|
$3,931,673
31,002 shares
|
— | 17 Jun 2025 |
| Eric K. Rowinsky |
3/4/5
Director
|
0.02%
|
$3,086,671
24,339 shares
|
— | 17 Jun 2025 |
| Stephen A. Sherwin |
3/4/5
Director
|
0.01%
|
$1,735,912
13,688 shares
|
— | 17 Jun 2025 |
How to read this table
Rows are grouped by holder and ranked first by SEC-reported ownership % when it is safely comparable, then by disclosed holdings value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.
Forms 3/4/5 flow
Insider trading overview
Net insider flow leans to selling over the last 12 months. Net value: -$1,034,229.
Buys
$585
Insiders: 1
Sells
$1,034,815
Insiders: 2
Net
-$1,034,229
Shares: -6,145
Window
Last 12 months
4 rolling buckets
Buy value
Sell value
Shares: 3
Shares: 6,148
| Window (months) | Buy shares | Sell shares | Buy value | Sell value | Net value |
|---|---|---|---|---|---|
| 0-3 | 0 | 0 | $0 | $0 | $0 |
| 3-6 | 3 | 3,408 | $585 | $665,664 | -$665,079 |
| 6-9 | 0 | 0 | $0 | $0 | $0 |
| 9-12 | 0 | 2,740 | $0 | $369,150 | -$369,150 |
Reporting owners
Insider holders from Forms 3/4/5
Showing 1-20 of 31 reporting-owner rows connected to BIOGEN INC.. Open a relationship link for the CIK-to-CIK filing trail.
Rows
31
Largest Forms 3/4/5 holder
Alexander J. Denner
Net 12M change
-$1,034,230
Latest report
01 May 2026
| Name | Relationship | Holdings Value | Past Year Net Change | Change % | Valuation | Report Date |
|---|---|---|---|---|---|---|
| Alexander J. Denner | Director | $163,208,552 | Mixed | 15 Jun 2022 | ||
| Michel Vounatsos | Chief Executive Officer, Director | $23,909,726 | Mixed | 18 Feb 2022 | ||
| Susan H. Alexander | EVP Chief Legal Officer | $11,981,713 | Mixed | 13 Feb 2026 | ||
| Stelios Papadopoulos | Director | $9,498,648 | Mixed | 15 Jun 2022 | ||
| Christopher A. Viehbacher | President and CEO, Director | $8,566,813 | Mixed | 13 Feb 2026 | ||
| Ginger Gregory | EVP, Human Resources | $4,498,136 | Mixed | 13 Feb 2026 | ||
| Chirfi Guindo | Head of Glob Prod Strat & Com | $4,139,728 | Mixed | 18 Feb 2022 | ||
| Caroline Dorsa | Director | $3,931,673 | Mixed | 17 Jun 2025 | ||
| Nicole Murphy | Head of Pharm Ops and Tech | $3,824,839 | +$585 | +0.02% | Filing P/S | 12 Feb 2026 |
| Richard Mulligan | Director | $3,744,552 | Mixed | 15 Jun 2022 | ||
| Michael R. McDonnell | EVP, Chief Financial Officer | $3,469,566 | Mixed | 10 Feb 2025 | ||
| Nancy Leaming | Director | $3,413,224 | Mixed | 01 Jul 2021 | ||
| Eric K. Rowinsky | Director | $3,086,671 | Mixed | 17 Jun 2025 | ||
| Alfred Sandrock | Head of Research & Development | $2,521,940 | Mixed | 07 Jun 2021 | ||
| Robin Kramer | Chief Financial Officer | $2,307,886 | Mixed | 13 Feb 2026 | ||
| Rachid Izzar | Head of Global Product Strat. | $2,215,192 | -$300,105 | -12% | Mixed | 13 Feb 2026 |
| Brian S. Posner | Director | $1,990,200 | Mixed | 31 Dec 2022 | ||
| Stephen A. Sherwin | Director | $1,735,912 | Mixed | 17 Jun 2025 | ||
| Adam Keeney | Head of Corporate Development | $1,676,320 | Mixed | 01 May 2026 | ||
| Priya Singhal | Head of Development | $1,607,261 | -$734,710 | -31% | Filing P/S | 13 Feb 2026 |
Recent insider transactions for BIOGEN INC.
Showing up to 300 recent insider transactions from the last 12 months.
| Insider | Symbol | Class | Transaction | % | SEC-reported value | SEC-reported price | Shares | Shares owned | Date | Ownership |
|---|---|---|---|---|---|---|---|---|---|---|
| Adam Keeney | BIIB | Common Stock | Tax liability | -6.67% | -455 | 6,365 | 01 May 2026 | Direct | ||
| Adam Keeney | BIIB | Common Stock | Options Exercise | 16% | 939 | 6,820 | 01 May 2026 | Direct | ||
| Adam Keeney | BIIB | Restricted Stock Unit | Options Exercise | -100% | -939 | 0 | 01 May 2026 | Direct | ||
| Sean Godbout | BIIB | Common Stock | Tax liability | -3.87% | -54 | 1,342 | 01 Apr 2026 | Direct | ||
| Sean Godbout | BIIB | Common Stock | Options Exercise | 14.9% | 181 | 1,396 | 01 Apr 2026 | Direct | ||
| Sean Godbout | BIIB | Restricted Stock Unit | Options Exercise | -33.2% | -181 | 364 | 01 Apr 2026 | Direct | ||
| Christopher A. Viehbacher | BIIB | Restricted Stock Unit | Award | 38,015 | 38,015 | 13 Feb 2026 | Direct | |||
| Priya Singhal | BIIB | Restricted Stock Unit | Award | 10,560 | 10,560 | 13 Feb 2026 | Direct | |||
| Nicole Murphy | BIIB | Restricted Stock Unit | Award | 10,560 | 10,560 | 13 Feb 2026 | Direct | |||
| Robin Kramer | BIIB | Restricted Stock Unit | Award | 8,450 | 8,450 | 13 Feb 2026 | Direct | |||
| Adam Keeney | BIIB | Restricted Stock Unit | Award | 8,025 | 8,025 | 13 Feb 2026 | Direct | |||
| Rachid Izzar | BIIB | Restricted Stock Unit | Award | 7,390 | 7,390 | 13 Feb 2026 | Direct | |||
| Jane Grogan | BIIB | Restricted Stock Unit | Award | 8,450 | 8,450 | 13 Feb 2026 | Direct | |||
| Ginger Gregory | BIIB | Restricted Stock Unit | Award | 8,025 | 8,025 | 13 Feb 2026 | Direct | |||
| Sean Godbout | BIIB | Restricted Stock Unit | Award | 1,800 | 1,800 | 13 Feb 2026 | Direct | |||
| Susan H. Alexander | BIIB | Restricted Stock Unit | Award | 8,450 | 8,450 | 13 Feb 2026 | Direct | |||
| Nicole Murphy | BIIB | Common Stock | Purchase | 0.02% | $585 | $195.04 | 3 | 19,611 | 12 Feb 2026 | Direct |
| Priya Singhal | BIIB | Common Stock | Sale | -24.8% | $531,548 | $199.83 | -2,660 | 8,043 | 09 Feb 2026 | Direct |
| Christopher A. Viehbacher | BIIB | Common Stock | Tax liability | -34.2% | -10,980 | 21,095 | 06 Feb 2026 | Direct | ||
| Christopher A. Viehbacher | BIIB | Common Stock | Options Exercise | 202.4% | 24,461 | 36,548 | 06 Feb 2026 | Direct | ||
| Christopher A. Viehbacher | BIIB | Restricted Stock Unit | Options Exercise | -73.1% | -24,461 | 9,009 | 06 Feb 2026 | Direct | ||
| Priya Singhal | BIIB | Common Stock | Tax liability | -24.9% | -2,468 | 7,432 | 06 Feb 2026 | Direct | ||
| Priya Singhal | BIIB | Common Stock | Options Exercise | 132.3% | 6,900 | 12,115 | 06 Feb 2026 | Direct | ||
| Priya Singhal | BIIB | Restricted Stock Unit | Options Exercise | -75.7% | -6,900 | 2,217 | 06 Feb 2026 | Direct | ||
| Nicole Murphy | BIIB | Common Stock | Tax liability | -17.9% | -3,339 | 15,307 | 06 Feb 2026 | Direct | ||
| Nicole Murphy | BIIB | Common Stock | Options Exercise | 71% | 8,725 | 21,016 | 06 Feb 2026 | Direct | ||
| Nicole Murphy | BIIB | Restricted Stock Unit | Options Exercise | -100% | -8,725 | 0 | 06 Feb 2026 | Direct | ||
| Robin Kramer | BIIB | Common Stock | Tax liability | -15.3% | -1,543 | 8,528 | 06 Feb 2026 | Direct | ||
| Robin Kramer | BIIB | Common Stock | Options Exercise | 66.4% | 5,003 | 12,535 | 06 Feb 2026 | Direct | ||
| Robin Kramer | BIIB | Restricted Stock Unit | Options Exercise | -100% | -5,003 | 0 | 06 Feb 2026 | Direct | ||
| Adam Keeney | BIIB | Common Stock | Tax liability | -30.6% | -1,583 | 3,597 | 06 Feb 2026 | Direct | ||
| Adam Keeney | BIIB | Common Stock | Options Exercise | 283% | 5,080 | 6,875 | 06 Feb 2026 | Direct | ||
| Adam Keeney | BIIB | Restricted Stock Unit | Options Exercise | -73.8% | -5,080 | 1,802 | 06 Feb 2026 | Direct | ||
| Rachid Izzar | BIIB | Common Stock | Tax liability | -21.6% | -2,038 | 7,399 | 06 Feb 2026 | Direct | ||
| Rachid Izzar | BIIB | Common Stock | Options Exercise | 140.7% | 6,889 | 11,786 | 06 Feb 2026 | Direct | ||
| Rachid Izzar | BIIB | Restricted Stock Unit | Options Exercise | -100% | -6,889 | 0 | 06 Feb 2026 | Direct | ||
| Jane Grogan | BIIB | Common Stock | Tax liability | -26.4% | -991 | 2,769 | 06 Feb 2026 | Direct | ||
| Jane Grogan | BIIB | Common Stock | Options Exercise | 235.4% | 3,258 | 4,642 | 06 Feb 2026 | Direct | ||
| Jane Grogan | BIIB | Restricted Stock Unit | Options Exercise | -70.2% | -3,258 | 1,385 | 06 Feb 2026 | Direct | ||
| Ginger Gregory | BIIB | Common Stock | Tax liability | -12.2% | -2,589 | 18,609 | 06 Feb 2026 | Direct | ||
| Ginger Gregory | BIIB | Common Stock | Options Exercise | 44% | 7,183 | 23,491 | 06 Feb 2026 | Direct | ||
| Ginger Gregory | BIIB | Restricted Stock Unit | Options Exercise | -100% | -7,183 | 0 | 06 Feb 2026 | Direct | ||
| Sean Godbout | BIIB | Common Stock | Tax liability | -34.7% | -359 | 676 | 06 Feb 2026 | Direct | ||
| Sean Godbout | BIIB | Common Stock | Options Exercise | 341.8% | 1,079 | 1,395 | 06 Feb 2026 | Direct | ||
| Sean Godbout | BIIB | Restricted Stock Unit | Options Exercise | -100% | -1,079 | 0 | 06 Feb 2026 | Direct | ||
| Susan H. Alexander | BIIB | Common Stock | Tax liability | -8.57% | -3,504 | 37,396 | 06 Feb 2026 | Direct | ||
| Susan H. Alexander | BIIB | Common Stock | Options Exercise | 26.4% | 9,046 | 43,321 | 06 Feb 2026 | Direct | ||
| Susan H. Alexander | BIIB | Restricted Stock Unit | Options Exercise | -100% | -9,046 | 0 | 06 Feb 2026 | Direct | ||
| Priya Singhal | BIIB | Common Stock | Sale | -10.7% | $134,116 | $179.30 | -748 | 6,271 | 02 Feb 2026 | Direct |
| Priya Singhal | BIIB | Common Stock | Tax liability | -7.66% | -582 | 7,019 | 30 Jan 2026 | Direct |
* marks a reported price that did not pass the local price check.