Biogen (BIIB)
Biogen on one page: short interest, daily short volume, fails to deliver, planned sales, large holders, 13F holders, financials, earnings dates and insider trades. Listed on Nasdaq, classified by the SEC as biological products, (no diagnostic substances).
5.5M
Short interest
settlement 2026-10-15
4.4
Days to cover
-0.5 days vs prior
55.7%
Short share of volume
2026-10-28
49,163
Fails to deliver
settlement 2026-09-28
Fri 5 Feb
Next earnings
estimated date
-$240K
Insider flow, 90 days
0 buys, 2 sells
As of 2026-10-28.
Short interest
FINRA, twice a month. The newest 48 settlements in the table, 48 in the chart. JSONAs of 15 October 2026, short interest in BIIB is 5,500,386 shares, down 317,411 shares over the last month. Over the last 48 readings it ranged from 2,576,781 shares (13 December 2024) to 6,777,473 shares (28 November 2025). At the reported average volume of 1.3M shares a day that is 4.4 days to cover.
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| Settlement | Shares short | Change | Avg daily volume | Days to cover |
|---|---|---|---|---|
| 2026-10-15 | 5,500,386 | -7.8% | 1,251,842 | 4.39 |
| 2026-09-30 | 5,965,892 | +2.5% | 1,225,961 | 4.87 |
| 2026-09-15 | 5,817,797 | +1.6% | 766,507 | 7.59 |
| 2026-08-31 | 5,726,631 | +10.3% | 661,593 | 8.66 |
| 2026-08-14 | 5,190,555 | -4.8% | 847,068 | 6.13 |
| 2026-07-31 | 5,453,901 | -9.1% | 1,153,245 | 4.73 |
| 2026-07-15 | 5,999,133 | +4.8% | 1,739,800 | 3.45 |
| 2026-06-30 | 5,723,194 | +10.3% | 1,382,477 | 4.14 |
| 2026-06-15 | 5,188,836 | +8.8% | 918,726 | 5.65 |
| 2026-05-29 | 4,771,495 | +0.9% | 1,063,313 | 4.49 |
| 2026-05-15 | 4,729,958 | +5.7% | 1,122,410 | 4.21 |
| 2026-04-30 | 4,475,470 | +1.4% | 1,247,291 | 3.59 |
| 2026-04-15 | 4,414,958 | +15.4% | 1,439,919 | 3.07 |
| 2026-03-31 | 3,826,441 | -11.7% | 1,104,246 | 3.47 |
| 2026-03-13 | 4,334,795 | +3.1% | 842,122 | 5.15 |
| 2026-02-27 | 4,202,912 | -7.5% | 908,274 | 4.63 |
| 2026-02-13 | 4,545,171 | -3.1% | 1,854,090 | 2.45 |
| 2026-01-30 | 4,692,637 | +0.3% | 1,296,294 | 3.62 |
| 2026-01-15 | 4,678,036 | +4.7% | 1,782,177 | 2.62 |
| 2025-12-31 | 4,466,337 | -32.2% | 2,674,703 | 1.67 |
| 2025-12-15 | 6,590,958 | -2.8% | 1,797,983 | 3.67 |
| 2025-11-28 | 6,777,473 | +10.4% | 2,080,199 | 3.26 |
| 2025-11-14 | 6,140,844 | +8.8% | 1,922,869 | 3.19 |
| 2025-10-31 | 5,644,654 | +8.7% | 1,566,934 | 3.60 |
| 2025-10-15 | 5,191,008 | +6.4% | 1,926,364 | 2.69 |
| 2025-09-30 | 4,880,043 | -4.8% | 1,636,581 | 2.98 |
| 2025-09-15 | 5,125,778 | +8.6% | 1,704,531 | 3.01 |
| 2025-08-29 | 4,720,975 | +13.6% | 1,316,930 | 3.58 |
| 2025-08-15 | 4,155,186 | +4.9% | 1,549,085 | 2.68 |
| 2025-07-31 | 3,959,672 | +1.6% | 1,423,928 | 2.78 |
| 2025-07-15 | 3,896,146 | -2.6% | 1,204,591 | 3.23 |
| 2025-06-30 | 4,000,596 | +18.0% | 1,304,129 | 3.07 |
| 2025-06-13 | 3,389,242 | -10.7% | 1,319,385 | 2.57 |
| 2025-05-30 | 3,795,285 | +13.6% | 1,780,738 | 2.13 |
| 2025-05-15 | 3,339,605 | +4.9% | 1,732,151 | 1.93 |
| 2025-04-30 | 3,184,274 | -7.6% | 1,469,396 | 2.17 |
| 2025-04-15 | 3,446,446 | +3.1% | 2,053,207 | 1.68 |
| 2025-03-31 | 3,343,887 | +1.0% | 1,602,989 | 2.09 |
| 2025-03-14 | 3,310,573 | -11.0% | 1,914,508 | 1.73 |
| 2025-02-28 | 3,719,971 | -4.2% | 1,620,071 | 2.30 |
| 2025-02-14 | 3,883,735 | +3.8% | 1,652,272 | 2.35 |
| 2025-01-31 | 3,741,109 | -0.8% | 1,286,729 | 2.91 |
| 2025-01-15 | 3,769,744 | +2.5% | 1,251,215 | 3.01 |
| 2024-12-31 | 3,676,606 | +42.7% | 1,668,315 | 2.20 |
| 2024-12-13 | 2,576,781 | -5.4% | 1,327,099 | 1.94 |
| 2024-11-29 | 2,722,956 | +1.0% | 1,546,388 | 1.76 |
| 2024-11-15 | 2,695,410 | -13.6% | 1,849,871 | 1.46 |
| 2024-10-31 | 3,120,565 | +1.7% | 1,240,246 | 2.52 |
Daily short volume
FINRA Reg SHO, the last 30 sessions. JSONAs of 28 October 2026, the short share of BIIB volume is 55.7%, down 4.0 points over the last five sessions. Over the last 30 readings it ranged from 35.8% (30 September 2026) to 78.2% (15 October 2026). The latest reading is 6.7 points below the 30-session average of 62.4%, on 978K shares reported.
| Date | Short volume | Total volume | Short share | Exempt |
|---|---|---|---|---|
| 2026-10-28 | 545K | 978K | 55.7% | 79 |
| 2026-10-27 | 309K | 537K | 57.6% | 0 |
| 2026-10-26 | 258K | 353K | 73.0% | 0 |
| 2026-10-23 | 357K | 491K | 72.7% | 0 |
| 2026-10-22 | 769K | 1.0M | 74.7% | 201 |
| 2026-10-21 | 187K | 314K | 59.7% | 0 |
| 2026-10-20 | 447K | 635K | 70.3% | 0 |
| 2026-10-19 | 226K | 357K | 63.2% | 0 |
| 2026-10-16 | 424K | 547K | 77.5% | 0 |
| 2026-10-15 | 451K | 577K | 78.2% | 365 |
| 2026-10-14 | 452K | 671K | 67.5% | 0 |
| 2026-10-13 | 277K | 384K | 72.2% | 100 |
| 2026-10-12 | 355K | 690K | 51.4% | 239 |
| 2026-10-09 | 183K | 349K | 52.3% | 362 |
| 2026-10-08 | 219K | 478K | 45.7% | 0 |
| 2026-10-07 | 278K | 528K | 52.7% | 14 |
| 2026-10-06 | 298K | 426K | 70.0% | 0 |
| 2026-10-05 | 223K | 408K | 54.7% | 0 |
| 2026-10-02 | 202K | 304K | 66.6% | 0 |
| 2026-10-01 | 380K | 747K | 50.9% | 0 |
| 2026-09-30 | 273K | 763K | 35.8% | 125 |
| 2026-09-29 | 246K | 471K | 52.2% | 1 |
| 2026-09-28 | 315K | 502K | 62.8% | 0 |
| 2026-09-25 | 228K | 301K | 75.7% | 301 |
| 2026-09-24 | 256K | 374K | 68.5% | 46 |
| 2026-09-23 | 338K | 487K | 69.4% | 10 |
| 2026-09-22 | 252K | 402K | 62.8% | 69 |
| 2026-09-21 | 201K | 334K | 60.2% | 0 |
| 2026-09-18 | 206K | 282K | 73.2% | 0 |
| 2026-09-17 | 111K | 246K | 45.1% | 190 |
Fails to deliver
SEC, the last 30 settlement dates with a fail. JSONAs of 28 September 2026, the fails-to-deliver balance in BIIB is 49,163 shares, up 49,105 shares over the last settlement date. Over the last 30 readings it ranged from 6 shares (26 May 2026) to 49,163 shares (28 September 2026). The latest reading sits at the top of that range.
| Settlement | Shares failed | Price | Value |
|---|---|---|---|
| 2026-09-28 | 49,163 | $227.60 | $11.2M |
| 2026-09-24 | 58 | $227.53 | $13K |
| 2026-09-23 | 300 | $225.36 | $68K |
| 2026-09-22 | 187 | $219.07 | $41K |
| 2026-09-21 | 61 | $215.50 | $13K |
| 2026-09-18 | 2,277 | $219.05 | $499K |
| 2026-09-17 | 634 | $216.01 | $137K |
| 2026-09-14 | 416 | $217.15 | $90K |
| 2026-09-11 | 386 | $215.43 | $83K |
| 2026-09-08 | 7,185 | $220.83 | $1.6M |
| 2026-09-04 | 17,209 | $224.51 | $3.9M |
| 2026-09-02 | 35 | $216.04 | $8K |
| 2026-08-28 | 991 | $221.50 | $220K |
| 2026-08-25 | 3,091 | $218.12 | $674K |
| 2026-08-24 | 93 | $216.78 | $20K |
| 2026-08-21 | 145 | $214.35 | $31K |
| 2026-08-07 | 135 | $206.28 | $28K |
| 2026-08-03 | 2,347 | $202.95 | $476K |
| 2026-07-17 | 8 | $208.92 | $2K |
| 2026-07-16 | 63 | $197.24 | $12K |
| 2026-06-30 | 2,785 | $216.63 | $603K |
| 2026-06-29 | 165 | $216.03 | $36K |
| 2026-06-25 | 215 | $199.59 | $43K |
| 2026-06-22 | 2,157 | $196.58 | $424K |
| 2026-06-15 | 692 | $200.05 | $138K |
| 2026-06-03 | 104 | $188.83 | $20K |
| 2026-05-27 | 97 | $193.08 | $19K |
| 2026-05-26 | 6 | $193.76 | $1K |
| 2026-05-22 | 516 | $189.47 | $98K |
| 2026-05-14 | 416 | $204.53 | $85K |
Insider trades
SEC Form 4, newest first. JSONInsiders at BIIB reported 2 open-market sells worth $240K in the last 90 days and no open-market buys. Latest filing: Godbout Sean (Chief Accounting Officer) on 2026-10-02.
| Date | Insider | Title | Type | Shares | Price | Value | Owned after |
|---|---|---|---|---|---|---|---|
| 2026-10-02 | Godbout Sean | Chief Accounting Officer | Tax withholding | 8 | $219.88 | $2K | 1K |
| 2026-10-02 | Godbout Sean | Chief Accounting Officer | Exercise or conversion | 27 | $0.00 | $0 | 1K |
| 2026-08-04 | Minor Lloyd | Director | Sell | 593 | $200.96 | $119K | 3K |
| 2026-08-03 | Minor Lloyd | Director | Sell | 593 | $203.34 | $121K | 3K |
| 2026-06-09 | HAWKINS WILLIAM A | Director | Grant | 2K | $0.00 | $0 | 10K |
| 2026-06-09 | SHERWIN STEPHEN A | Director | Grant | 2K | $0.00 | $0 | 15K |
| 2026-06-09 | Rowinsky Eric K | Director | Grant | 2K | $0.00 | $0 | 26K |
| 2026-06-09 | Mantas Jesus B | Director | Grant | 2K | $0.00 | $0 | 11K |
| 2026-06-09 | LANGER SUSAN | Director | Grant | 2K | $0.00 | $0 | 7K |
| 2026-06-09 | Patolawala Monish D | Director | Grant | 2K | $0.00 | $0 | 5K |
| 2026-06-09 | Pangalos Menelas N | Director | Grant | 2K | $0.00 | $0 | 4K |
| 2026-06-09 | Pangalos Menelas N | Director | Exercise or conversion | 2K | $0.00 | $0 | 2K |
| 2026-06-09 | Minor Lloyd | Director | Grant | 2K | $0.00 | $0 | 4K |
| 2026-06-09 | Freire Maria C | Director | Grant | 2K | $0.00 | $0 | 9K |
| 2026-05-01 | Keeney Adam | Head of Corporate Development | Tax withholding | 455 | $187.06 | $85K | 6K |
| 2026-05-01 | Keeney Adam | Head of Corporate Development | Exercise or conversion | 939 | $0.00 | $0 | 7K |
| 2026-04-01 | Godbout Sean | Chief Accounting Officer | Tax withholding | 54 | $183.78 | $10K | 1K |
| 2026-04-01 | Godbout Sean | Chief Accounting Officer | Exercise or conversion | 181 | $0.00 | $0 | 1K |
| 2026-02-12 | Murphy Nicole | Head of Pharm Ops and Tech | Buy | 3 | $195.03 | $585 | 20K |
| 2026-02-09 | Singhal Priya | Head of Development | Sell | 3K | $199.83 | $532K | 8K |
| 2026-02-06 | Viehbacher Christopher | President and CEO | Tax withholding | 7K | $201.18 | $1.3M | 30K |
| 2026-02-06 | Viehbacher Christopher | President and CEO | Exercise or conversion | 15K | $0.00 | $0 | 37K |
| 2026-02-06 | Viehbacher Christopher | President and CEO | Tax withholding | 4K | $201.18 | $876K | 21K |
| 2026-02-06 | Viehbacher Christopher | President and CEO | Exercise or conversion | 9K | $0.00 | $0 | 25K |
| 2026-02-06 | Singhal Priya | Head of Development | Tax withholding | 1K | $201.18 | $284K | 11K |
| 2026-02-06 | Singhal Priya | Head of Development | Exercise or conversion | 5K | $0.00 | $0 | 12K |
| 2026-02-06 | Singhal Priya | Head of Development | Tax withholding | 1K | $201.18 | $212K | 7K |
| 2026-02-06 | Singhal Priya | Head of Development | Exercise or conversion | 2K | $0.00 | $0 | 8K |
| 2026-02-06 | Murphy Nicole | Head of Pharm Ops and Tech | Tax withholding | 1K | $201.18 | $283K | 20K |
| 2026-02-06 | Murphy Nicole | Head of Pharm Ops and Tech | Exercise or conversion | 5K | $0.00 | $0 | 21K |
| 2026-02-06 | Murphy Nicole | Head of Pharm Ops and Tech | Tax withholding | 914 | $201.18 | $184K | 16K |
| 2026-02-06 | Murphy Nicole | Head of Pharm Ops and Tech | Exercise or conversion | 2K | $0.00 | $0 | 17K |
| 2026-02-06 | Murphy Nicole | Head of Pharm Ops and Tech | Tax withholding | 1K | $201.18 | $205K | 15K |
| 2026-02-06 | Murphy Nicole | Head of Pharm Ops and Tech | Exercise or conversion | 2K | $0.00 | $0 | 16K |
| 2026-02-06 | Kramer Robin | Chief Financial Officer | Tax withholding | 1K | $201.18 | $214K | 11K |
| 2026-02-06 | Kramer Robin | Chief Financial Officer | Exercise or conversion | 4K | $0.00 | $0 | 13K |
| 2026-02-06 | Kramer Robin | Chief Financial Officer | Tax withholding | 207 | $201.18 | $42K | 9K |
| 2026-02-06 | Kramer Robin | Chief Financial Officer | Exercise or conversion | 703 | $0.00 | $0 | 9K |
| 2026-02-06 | Kramer Robin | Chief Financial Officer | Tax withholding | 273 | $201.18 | $55K | 9K |
| 2026-02-06 | Kramer Robin | Chief Financial Officer | Exercise or conversion | 789 | $0.00 | $0 | 9K |
| 2026-02-06 | Keeney Adam | Head of Corporate Development | Tax withholding | 994 | $201.18 | $200K | 6K |
| 2026-02-06 | Keeney Adam | Head of Corporate Development | Exercise or conversion | 3K | $0.00 | $0 | 7K |
| 2026-02-06 | Keeney Adam | Head of Corporate Development | Tax withholding | 589 | $201.18 | $118K | 4K |
| 2026-02-06 | Keeney Adam | Head of Corporate Development | Exercise or conversion | 2K | $0.00 | $0 | 4K |
| 2026-02-06 | Izzar Rachid | Head of Global Product Strat. | Tax withholding | 775 | $201.18 | $156K | 11K |
| 2026-02-06 | Izzar Rachid | Head of Global Product Strat. | Exercise or conversion | 3K | $0.00 | $0 | 12K |
| 2026-02-06 | Izzar Rachid | Head of Global Product Strat. | Tax withholding | 458 | $201.18 | $92K | 9K |
| 2026-02-06 | Izzar Rachid | Head of Global Product Strat. | Exercise or conversion | 2K | $0.00 | $0 | 9K |
| 2026-02-06 | Izzar Rachid | Head of Global Product Strat. | Tax withholding | 805 | $201.18 | $162K | 7K |
| 2026-02-06 | Izzar Rachid | Head of Global Product Strat. | Exercise or conversion | 2K | $0.00 | $0 | 8K |
| 2026-02-06 | Grogan Jane | Head of Research | Tax withholding | 584 | $201.18 | $117K | 4K |
| 2026-02-06 | Grogan Jane | Head of Research | Exercise or conversion | 2K | $0.00 | $0 | 5K |
| 2026-02-06 | Grogan Jane | Head of Research | Tax withholding | 407 | $201.18 | $82K | 3K |
| 2026-02-06 | Grogan Jane | Head of Research | Exercise or conversion | 1K | $0.00 | $0 | 3K |
| 2026-02-06 | Gregory Ginger | EVP, Human Resources | Tax withholding | 1K | $201.18 | $228K | 22K |
| 2026-02-06 | Gregory Ginger | EVP, Human Resources | Exercise or conversion | 4K | $0.00 | $0 | 23K |
| 2026-02-06 | Gregory Ginger | EVP, Human Resources | Tax withholding | 666 | $201.18 | $134K | 20K |
| 2026-02-06 | Gregory Ginger | EVP, Human Resources | Exercise or conversion | 2K | $0.00 | $0 | 20K |
| 2026-02-06 | Gregory Ginger | EVP, Human Resources | Tax withholding | 791 | $201.18 | $159K | 19K |
| 2026-02-06 | Gregory Ginger | EVP, Human Resources | Exercise or conversion | 2K | $0.00 | $0 | 19K |
| 2026-02-06 | Godbout Sean | Chief Accounting Officer | Tax withholding | 180 | $201.18 | $36K | 1K |
| 2026-02-06 | Godbout Sean | Chief Accounting Officer | Exercise or conversion | 517 | $0.00 | $0 | 1K |
| 2026-02-06 | Godbout Sean | Chief Accounting Officer | Tax withholding | 103 | $201.18 | $21K | 878 |
| 2026-02-06 | Godbout Sean | Chief Accounting Officer | Exercise or conversion | 305 | $0.00 | $0 | 981 |
| 2026-02-06 | Godbout Sean | Chief Accounting Officer | Tax withholding | 76 | $201.18 | $15K | 676 |
| 2026-02-06 | Godbout Sean | Chief Accounting Officer | Exercise or conversion | 257 | $0.00 | $0 | 752 |
| 2026-02-06 | ALEXANDER SUSAN H | EVP Chief Legal Officer | Tax withholding | 2K | $201.18 | $305K | 42K |
| 2026-02-06 | ALEXANDER SUSAN H | EVP Chief Legal Officer | Exercise or conversion | 5K | $0.00 | $0 | 43K |
| 2026-02-06 | ALEXANDER SUSAN H | EVP Chief Legal Officer | Tax withholding | 931 | $201.18 | $187K | 38K |
| 2026-02-06 | ALEXANDER SUSAN H | EVP Chief Legal Officer | Exercise or conversion | 2K | $0.00 | $0 | 39K |
| 2026-02-06 | ALEXANDER SUSAN H | EVP Chief Legal Officer | Tax withholding | 1K | $201.18 | $213K | 37K |
| 2026-02-06 | ALEXANDER SUSAN H | EVP Chief Legal Officer | Exercise or conversion | 2K | $0.00 | $0 | 38K |
| 2026-02-02 | Singhal Priya | Head of Development | Sell | 748 | $179.30 | $134K | 6K |
| 2026-01-30 | Singhal Priya | Head of Development | Tax withholding | 582 | $179.89 | $105K | 7K |
| 2026-01-30 | Singhal Priya | Head of Development | Exercise or conversion | 2K | $0.00 | $0 | 8K |
| 2025-12-01 | Viehbacher Christopher | President and CEO | Tax withholding | 3K | $177.78 | $605K | 16K |
| 2025-12-01 | Viehbacher Christopher | President and CEO | Exercise or conversion | 7K | $0.00 | $0 | 20K |
| 2025-10-31 | Grogan Jane | Head of Research | Tax withholding | 337 | $154.27 | $52K | 2K |
| 2025-10-31 | Grogan Jane | Head of Research | Exercise or conversion | 695 | $0.00 | $0 | 2K |
| 2025-10-02 | Godbout Sean | Chief Accounting Officer | Tax withholding | 8 | $155.25 | $1K | 495 |
| 2025-10-02 | Godbout Sean | Chief Accounting Officer | Exercise or conversion | 26 | $0.00 | $0 | 503 |
| 2025-09-02 | Singhal Priya | Head of Development | Sell | 517 | $133.55 | $69K | 6K |
| 2025-08-29 | Singhal Priya | Head of Development | Tax withholding | 807 | $132.22 | $107K | 6K |
| 2025-08-29 | Singhal Priya | Head of Development | Exercise or conversion | 2K | $0.00 | $0 | 7K |
| 2025-07-08 | Izzar Rachid | Head of Global Product Strat. | Sell | 2K | $135.00 | $300K | 6K |
| 2025-06-17 | Minor Lloyd | Director | Grant | 2K | $0.00 | $0 | 2K |
| 2025-06-17 | Patolawala Monish D | Director | Grant | 2K | $0.00 | $0 | 4K |
| 2025-06-17 | Mantas Jesus B | Director | Grant | 2K | $0.00 | $0 | 10K |
| 2025-06-17 | HAWKINS WILLIAM A | Director | Grant | 2K | $0.00 | $0 | 9K |
| 2025-06-17 | Freire Maria C | Director | Grant | 2K | $0.00 | $0 | 7K |
| 2025-06-17 | Rowinsky Eric K | Director | Grant | 2K | $0.00 | $0 | 24K |
| 2025-06-17 | SHERWIN STEPHEN A | Director | Grant | 2K | $0.00 | $0 | 14K |
| 2025-06-17 | LANGER SUSAN | Director | Grant | 2K | $0.00 | $0 | 5K |
| 2025-06-17 | DORSA CAROLINE | Director | Grant | 3K | $0.00 | $0 | 31K |
| 2025-05-19 | Singhal Priya | Head of Development | Sell | 4K | $126.25 | $481K | 5K |
| 2025-05-02 | DORSA CAROLINE | Director | Buy | 1K | $122.72 | $152K | 28K |
| 2025-05-01 | Keeney Adam | Head of Corporate Development | Exercise or conversion | 938 | $0.00 | $0 | 3K |
| 2025-05-01 | Keeney Adam | Head of Corporate Development | Tax withholding | 454 | $120.93 | $55K | 2K |
| 2025-03-07 | SHERWIN STEPHEN A | Director | Sell | 9K | $150.02 | $1.3M | 11K |
| 2025-02-10 | Izzar Rachid | Head of Global Product Strat. | Tax withholding | 445 | $142.54 | $63K | 9K |
Form 4 filings are due within two business days of the trade. Insiders sell for many reasons that say nothing about the company; open-market buys are rarer.
Planned sales (Form 144)
Newest first. JSON4 Form 144 notices on file for BIIB worth $905K at the prices reported; 2 in the last 90 days worth $240K. Latest: Minor Lloyd filed on 2026-08-04 to sell 593 shares ($119K) from 2026-08-04.
| Filed | Seller | Shares | Market value | Of outstanding | Sale from | Broker |
|---|---|---|---|---|---|---|
| 2026-08-04 | Minor LloydDirector | 593 | $119K | 0.000% | 2026-08-04 | Fidelity Brokerage Services LLC |
| 2026-08-03 | Minor LloydDirector | 593 | $121K | 0.000% | 2026-08-03 | Fidelity Brokerage Services LLC |
| 2026-02-09 | Singhal PriyaOfficer | 3K | $532K | 0.002% | 2026-02-09 | Fidelity Brokerage Services LLC |
| 2026-02-02 | Singhal PriyaOfficer | 748 | $134K | 0.001% | 2026-02-02 | Fidelity Brokerage Services LLC |
Large holders (13D and 13G)
One row per reporting person with its latest filing, newest first. JSON5 holders report 5% or more of BIIB in their latest filing, all on Schedule 13G (passive). The largest reported stake is FMR LLC at 12.4% of the class (18,294,524 shares), filed 2026-08-06 for an event on 2026-06-30.
| Filed | Form | Holder | Shares | Of class | Event |
|---|---|---|---|---|---|
| 2026-08-06 | 13G/Ano. 3 | FMR LLCparent holding company | 18.3M | 12.4% | 2026-06-30 |
| 2026-08-06 | 13G/Ano. 3 | Abigail P. Johnsonindividual | 18.3M | 12.4% | 2026-06-30 |
| 2026-04-29 | 13G | Vanguard Capital Managementinvestment adviser | 11.0M | 7.5% | 2026-03-31 |
| 2026-03-26 | 13G/Ano. 13 | The Vanguard Groupinvestment adviser | 0 | 0.0% | 2026-03-13 |
| 2025-11-13 | 13G/Ano. 27 | PRIMECAP MANAGEMENT CO/CA/investment adviser | 15.0M | 10.2% | 2025-09-30 |
| 2025-11-10 | 13G | STATE STREET CORPORATIONparent holding company | 7.3M | 5.0% | 2025-09-30 |
13F holders
Tracked managers holding BIIB at their latest 13F. JSON7 of the 30 tracked managers held BIIB at their latest 13F, $633.8M in total at quarter-end prices. AQR Capital Management is the largest at $416.9M (0.1% of its portfolio) as of 2026-06-30. Over the prior quarter 4 added shares and 3 cut.
| Fund | Quarter | Shares | Value | Of portfolio | Change in shares |
|---|---|---|---|---|---|
| AQR Capital Management | 2026-06-30 | 1.9M | $416.9M | 0.15% | +13K |
| Citadel Advisors | 2026-06-30 | 418K | $90.4M | 0.01% | +280K |
| Fisher Asset Management | 2026-06-30 | 338K | $73.0M | 0.02% | +25K |
| Point72 Asset Management | 2026-06-30 | 88K | $19.0M | 0.02% | -721K |
| Renaissance Technologies | 2026-06-30 | 78K | $16.8M | 0.02% | -126K |
| D. E. Shaw & Co. | 2026-06-30 | 74K | $16.1M | 0.01% | new |
| Two Sigma Investments | 2026-06-30 | 7K | $1.5M | 0.00% | -2K |
Only the 30 tracked managers on the funds hub; a 13F reports long positions in US listed stock at quarter end, 45 days late, and says nothing about shorts or positions sold since.
Financials
SEC XBRL, as filed. JSONIn Q1 FY 2026 (quarter ended 2026-03-31) Biogen reported revenue of $2.48B, up 1.9% from the same quarter a year earlier, and net income of $319.5M (2.15 diluted EPS). In FY 2025 it generated $2.20B of operating cash flow.
- Debt
- $6.29B
- Total assets
- $29.48B
- Shares outstanding
- 147,637,117
Quarterly, last 8 quarters
| Quarter | Period end | Revenue | Net income | Margin | Diluted EPS |
|---|---|---|---|---|---|
| Q1 FY 2026 | 2026-03-31 | $2.48B | $319.5M | 12.9% | 2.15 |
| Q4 FY 2025derived | 2025-12-31 | $2.28B | -$48.9M | -2.1% | n/a |
| Q3 FY 2025 | 2025-09-30 | $2.53B | $466.5M | 18.4% | 3.17 |
| Q2 FY 2025 | 2025-06-30 | $2.65B | $634.8M | 24.0% | 4.33 |
| Q1 FY 2025 | 2025-03-31 | $2.43B | $240.5M | 9.9% | 1.64 |
| Q4 FY 2024derived | 2024-12-31 | $2.45B | $266.7M | 10.9% | n/a |
| Q3 FY 2024 | 2024-09-30 | $2.47B | $388.5M | 15.8% | 2.66 |
| Q2 FY 2024 | 2024-06-30 | $2.46B | $583.6M | 23.7% | 4.00 |
Fiscal years, with buybacks and dividends
| Fiscal year | Ends | Revenue | Net income | Operating cash flow | Capex | Buybacks | Dividends |
|---|---|---|---|---|---|---|---|
| FY 2025 | 2025-12-31 | $9.89B | $1.29B | $2.20B | $153.8M | n/a | n/a |
| FY 2024 | 2024-12-31 | $9.68B | $1.63B | $2.88B | $153.7M | $0 | n/a |
| FY 2023 | 2023-12-31 | $9.84B | $1.16B | $1.55B | $277.0M | $0 | n/a |
| FY 2022 | 2022-12-31 | $10.17B | $3.05B | $1.38B | $240.3M | $750.0M | n/a |
| FY 2021 | 2021-12-31 | $10.98B | $1.56B | $3.64B | $258.1M | $1.80B | n/a |
Quarters are the three-month figures the company reports; a fourth quarter marked derived is the fiscal year less the three reported quarters, since companies report it only inside the 10-K. Fiscal years are the annual figures. Buybacks are the cash the company paid to repurchase its common stock in the year, not the amount authorized. Balance sheet lines are as of 2026-03-31; shares outstanding as of 2026-04-27 from the cover page.
What this page is
Biogen in the regulatory record
Regulators publish company data in separate files that never sit next to each other: FINRA's twice-monthly short interest, its daily short sale volume, the SEC's fails-to-deliver counts, and each insider's Form 4. A company page puts those series for one ticker on one URL, with planned sales, large holders, 13F holders and financials beside them, so the short position, the daily flow, the settlement fails and what insiders are doing can be read together.
Each section has its own history table, a one-line summary of the latest figures and its own JSON and CSV links, and says when its source last updated.
This page follows Biogen (BIIB), SEC CIK 875045, listed on Nasdaq, classified by the SEC as biological products, (no diagnostic substances). The cross-market tables live on the short interest and insider transactions hubs.
Source and updates
- Short interest
- FINRA consolidated short interestSource: FINRA.Twice a month, about eight business days after settlement. Latest 2026-10-15.JSON and CSV
- Daily short volume
- FINRA Reg SHO daily filesSource: FINRA.Every trading day, the morning after FINRA posts it. Latest 2026-10-28.JSON and CSV
- Fails to deliver
- SEC fails-to-deliver dataSource: SEC.Twice a month, a few weeks after the half month ends. Latest 2026-09-28.JSON and CSV
- Planned sales
- SEC EDGAR Form 144Source: SEC.New notices appear shortly after the SEC posts them; a notice is filed on or before the sale. Latest 2026-08-04.JSON and CSV
- Large holders
- SEC EDGAR Schedule 13D and 13GSource: SEC.New filings appear shortly after the SEC posts them. A 13D is due within five business days of crossing 5%; a 13G follows the passive schedule. Latest 2026-08-06.JSON and CSV
- 13F holders
- SEC EDGAR Form 13F-HRSource: SEC.Quarterly, filed within 45 days of quarter end; 30 tracked managers. Latest 2026-06-30.JSON and CSV
- Financials
- SEC EDGAR 10-K and 10-Q filingsSource: SEC.Weekly; values are as filed in the 10-Q and 10-K. Latest 2026-03-31.JSON and CSV
- Earnings dates
- SEC EDGAR 8-K filings (Item 2.02)Source: SEC.Twice a day. Reported dates come from the company's 8-K filings; the next date is marked as an estimate until the 8-K arrives. Latest 2026-10-28.JSON and CSV
- Insider trades
- SEC EDGAR Form 4Source: SEC.New filings appear shortly after the SEC posts them; they're due two business days after the trade. Latest 2026-10-02.JSON and CSV
- Company record
- EDGAR filing index for CIK 875045Ticker, name and exchange from the SEC's company list, refreshed weekly.
- Rate limits
- 10 requests a minute without a key, 30 with a free key from a free account.
How to read it
- Read the position against the flow: rising short interest with a high daily short share is new shorting; rising short interest with a normal short share is old shorts holding on.
- Insider buys next to a large short position are rare and stand out; insider sells next to one are common and mean little.
- Fails to deliver matter relative to the float, not in absolute shares; a million failed shares in a mega cap is noise.
Analysis of what the data shows, not advice. XOOMAR does not recommend buying, selling or holding anything.
Other companies the SEC classifies as biological products, (no diagnostic substances)
Other company pages
Datasets
Frequently Asked Questions
How much of BIIB is sold short?
5,500,386 shares were held short at the 2026-10-15 settlement, 4.4 days of average volume. FINRA publishes the next count about eight business days after the 15th and the last business day of the month.
What is BIIB's daily short volume?
On 2026-10-28, 544,819 of the 978,089 BIIB shares reported to FINRA were sold short, 55.7% of the day's reported volume. Short volume is a flow for one day, not a position.
Does BIIB have fails to deliver?
The SEC's latest file shows 49,163 BIIB shares failed to deliver at settlement 2026-09-28. Fails are reported per settlement date and published twice a month with a lag.
Are BIIB insiders buying or selling?
Insiders at BIIB reported 2 open-market sells worth $240K in the last 90 days and no open-market buys. Latest filing: Godbout Sean (Chief Accounting Officer) on 2026-10-02.
Have BIIB insiders filed to sell?
4 Form 144 notices on file for BIIB worth $905K at the prices reported; 2 in the last 90 days worth $240K. Latest: Minor Lloyd filed on 2026-08-04 to sell 593 shares ($119K) from 2026-08-04.
Who owns 5% or more of BIIB?
5 holders report 5% or more of BIIB in their latest filing, all on Schedule 13G (passive). The largest reported stake is FMR LLC at 12.4% of the class (18,294,524 shares), filed 2026-08-06 for an event on 2026-06-30.
What did BIIB report last quarter?
In Q1 FY 2026 (quarter ended 2026-03-31) Biogen reported revenue of $2.48B, up 1.9% from the same quarter a year earlier, and net income of $319.5M (2.15 diluted EPS). In FY 2025 it generated $2.20B of operating cash flow.
Which tracked 13F managers own BIIB?
7 of the 30 tracked 13F managers held BIIB shares at their latest filing, $633.8M in all. The largest: Cliff Asness's AQR Capital Management (1.9M shares, $416.9M), Ken Griffin's Citadel Advisors (418K shares, $90.4M), Ken Fisher's Fisher Asset Management (338K shares, $73.0M), Steve Cohen's Point72 Asset Management (88K shares, $19.0M), Renaissance Technologies (78K shares, $16.8M), D. E. Shaw & Co. (74K shares, $16.1M). The table above lists all 7.
Data on this page is provided for informational purposes only and is not financial advice. See our editorial policy.