BIIB · Biogen Inc.
Shares sold short and not yet covered, reported twice monthly. Days to cover is the reported short position divided by average daily volume.
BIIB Latest Reported Short Interest
FINRA reported 5,190,555 BIIB shares sold short as of the August 14, 2026 settlement date, a decrease of 263,346 shares. Days to cover was 6.13 based on FINRA's reported average daily volume.
Official FINRA short-interest data · share counts are restated for subsequent stock splits
BIIB Short Interest Forecast
Equibles' model estimates 5,337,390 shares sold short for the August 31, 2026 settlement, +2.8% versus the latest reported position, with a likely range of 4,821,206 to 5,864,547 shares. This model prediction uses FINRA data through August 31, 2026; FINRA's official release is expected September 10, 2026.
Expected Aug 31 short interest
as of Aug 31 Low confidence 55% chance it fallsPeer-relative percentile rank across all stocks reporting short interest at the latest settlement date (2026-08-14). Weighted mean of the available factors (short interest 30%, days to cover 20%, price vs VWAP 15%, short-volume trend 15%, short-interest change 10%, fails-to-deliver 10%) plus catalyst boosts (price spike, volume surge, earnings within days), capped at +20 and clamped to 100.
Short Interest History
| Settlement Date | Current Position | Previous Position | Change | Days to Cover |
|---|---|---|---|---|
|
2026-09-15
Scheduled
FINRA publishes Sep 24
|
— | — | — | — |
|
2026-08-31
Scheduled
FINRA publishes Sep 10
|
— | — | — | — |
| 2026-08-14 | 5,190,555 | 5,453,901 | -263,346 | 6.13 |
| 2026-07-31 | 5,453,901 | 5,999,133 | -545,232 | 4.73 |
| 2026-07-15 | 5,999,133 | 5,723,194 | +275,939 | 3.45 |
| 2026-06-30 | 5,723,194 | 5,188,836 | +534,358 | 4.14 |
| 2026-06-15 | 5,188,836 | 4,771,495 | +417,341 | 5.65 |
| 2026-05-29 | 4,771,495 | 4,729,958 | +41,537 | 4.49 |
| 2026-05-15 | 4,729,958 | 4,475,470 | +254,488 | 4.21 |
| 2026-04-30 | 4,475,470 | 4,414,958 | +60,512 | 3.59 |
| 2026-04-15 | 4,414,958 | 3,826,441 | +588,517 | 3.07 |
| 2026-03-31 | 3,826,441 | 4,334,795 | -508,354 | 3.47 |
| 2026-03-13 | 4,334,795 | 4,202,912 | +131,883 | 5.15 |
| 2026-02-27 | 4,202,912 | 4,545,171 | -342,259 | 4.63 |
| 2026-02-13 | 4,545,171 | 4,692,637 | -147,466 | 2.45 |
| 2026-01-30 | 4,692,637 | 4,678,036 | +14,601 | 3.62 |
| 2026-01-15 | 4,678,036 | 4,466,337 | +211,699 | 2.62 |
| 2025-12-31 | 4,466,337 | 6,590,958 | -2,124,621 | 1.67 |
| 2025-12-15 | 6,590,958 | 6,777,473 | -186,515 | 3.67 |
| 2025-11-28 | 6,777,473 | 6,140,844 | +636,629 | 3.26 |
| 2025-11-14 | 6,140,844 | 5,644,654 | +496,190 | 3.19 |
| 2025-10-31 | 5,644,654 | 5,191,008 | +453,646 | 3.60 |
| 2025-10-15 | 5,191,008 | 4,880,043 | +310,965 | 2.69 |
| 2025-09-30 | 4,880,043 | 5,125,778 | -245,735 | 2.98 |
| 2025-09-15 | 5,125,778 | 4,720,975 | +404,803 | 3.01 |
Full FINRA short interest reporting calendar