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EOD US-equity data for investors and AI agents

Data is end-of-day, not real-time, and not investment advice

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BIIB short positioning

Twice-monthly snapshots of open short positions.

Settlement 2026-07-31
Short % of Float3.7%147,153,000 float shares
Days to Cover4.71,153,245 average daily volume
Open Short Position5,453,901Biogen Inc. Common Stock
Change vs Previous-545,232-9.1%

Short interest history

Twice-monthly snapshots of open short positions.

SettlementShort PositionChangeChange %Days to CoverShort % Float
Jul 31, 20265,453,901-545,232-9.1%4.73.7%
Jul 15, 20265,999,133+275,939+4.8%3.54.1%
Jun 30, 20265,723,194+534,358+10.3%4.13.9%

Short interest is an open-position snapshot published twice monthly. It is not daily short-sale volume.

Daily off-exchange short volume

FINRA-reported short-sale transaction flow for the last 30 calendar days.

Trade DateShort VolumeShort ExemptFINRA TotalShort Volume %Facilities
Aug 21, 2026128,331600262,52648.9%3
Aug 20, 2026150,8021307,96849.0%3
Aug 19, 2026143,2010279,20051.3%3
Aug 18, 2026170,9570287,24459.5%3
Aug 17, 2026130,238406224,82457.9%3
Aug 14, 2026111,6980187,95059.4%3
Aug 13, 2026176,9121327,65054.0%3
Aug 12, 2026178,873101293,64260.9%3
Aug 11, 2026183,209310362,61950.5%3
Aug 10, 2026142,524278272,75852.3%3
Aug 7, 2026161,83721,142290,82655.6%3
Aug 6, 2026134,528138344,24639.1%3
Aug 5, 2026181,69749330,27955.0%3
Aug 4, 2026224,30422564,02639.8%3
Aug 3, 2026157,83273337,86346.7%3
Jul 31, 2026210,08740466,16445.1%3
Jul 30, 2026270,0560383,71970.4%3
Jul 29, 2026585,8522521,084,84954.0%3
Jul 28, 2026233,5824614,10638.0%3
Jul 27, 2026140,40840277,38950.6%3
Jul 24, 2026125,354284202,62061.9%3

Daily short volume is transaction flow reported through FINRA facilities. It does not measure open short positions and is not consolidated exchange-wide volume.