Biogen (BIIB) Short Interest Ratio & Short Volume $119.26 +4.09 (+3.55%) As of 04/14/2025 04:00 PM Eastern Add Compare Share Share Short Interest Stock AnalysisAnalyst ForecastsChartCompetitorsEarningsFinancialsHeadlinesInsider TradesOptions ChainOwnershipSEC FilingsShort InterestSustainabilityTrendsBuy This Stock Biogen Short Interest DataBiogen (BIIB) has a short interest of 3.34 million shares, representing 2.29% of the float (the number of shares available for trading by the public). This marks a 0.91% increase in short interest from the previous month. The short interest ratio (days to cover) is 2.0, indicating that it would take 2.0 days of the average trading volume of 1.35 million shares to cover all short positions.Current Short Interest3,340,000 sharesPrevious Short Interest3,310,000 sharesChange Vs. Previous Month+0.91%Dollar Volume Sold Short$457.05 millionShort Interest Ratio2.0 Days to CoverLast Record DateMarch 31, 2025Outstanding Shares146,375,000 sharesFloat Size145,630,000 sharesShort Percent of Float2.29%Today's Trading Volume1,687,602 sharesAverage Trading Volume1,354,737 sharesToday's Volume Vs. Average125% Short Selling Biogen? Sign up to receive the latest short interest report for Biogen and its competitors with MarketBeat's FREE newsletter. Email Address Skip Charts & View Short Interest HistoryShort Interest ChartDays to Cover ChartShort Percent of Float ChartBIIB Short Interest Over TimeBIIB Days to Cover Over TimeBIIB Percentage of Float Shorted Over Time Remove Ads Biogen Short Interest History Export to ExcelReport DateTotal Shares Sold ShortDollar Volume Sold ShortChange from Previous ReportPercentage of Float ShortedDays to CoverPrice on Report Date 3/31/20253,340,000 shares $457.05 million +0.9%2.3%2 $136.84 3/15/20253,310,000 shares $461.55 million -11.0%2.3%2.1 $139.44 2/28/20253,720,000 shares $522.66 million -4.1%2.6%2.4 $140.50 2/15/20253,880,000 shares $532.84 million +3.7%2.7%2.6 $137.33 1/31/20253,740,000 shares $538.30 million -0.8%2.6%2.5 $143.93 1/15/20253,770,000 shares $531.57 million +2.5%2.6%2.5 $141.00 12/31/20243,680,000 shares $562.75 million +42.6%2.5%2.5 $152.92 12/15/20242,580,000 shares $387.08 million -5.2%1.8%1.7 $150.03 11/30/20242,720,000 shares $436.91 million +0.7%1.9%1.9 $160.63 11/15/20242,700,000 shares $431.97 million -13.5%1.9%2 $159.99 Get the Latest News and Ratings for BIIB and Related StocksEnter your email address below to receive the latest news and analysts' ratings for Biogen and its competitors with MarketBeat's FREE daily newsletter. 10/31/20243,120,000 shares $542.88 million +1.6%2.2%2.7 $174.00 10/15/20243,070,000 shares $588.06 million +7.7%2.1%2.8 $191.55 9/30/20242,850,000 shares $552.44 million -22.3%2.0%2.7 $193.84 9/15/20243,670,000 shares $717.96 million +9.9%2.5%3.6 $195.63 8/31/20243,340,000 shares $683.90 million +24.6%2.3%3.4 $204.76 8/15/20242,680,000 shares $540.37 million -1.8%1.9%2.6 $201.63 7/31/20242,730,000 shares $582.04 million -24.8%1.9%2.6 $213.20 7/15/20243,630,000 shares $804.34 million +32.5%2.5%3.4 $221.58 6/30/20242,740,000 shares $635.19 million -10.8%1.9%2.5 $231.82 6/15/20243,070,000 shares $711.29 million +1.7%2.1%2.7 $231.69 5/31/20243,020,000 shares $679.32 million -13.2%2.1%2.5 $224.94 5/15/20243,480,000 shares $818.91 million +10.5%2.4%2.9 $235.32 4/30/20243,150,000 shares $676.68 million -3.4%2.2%2.4 $214.82 4/15/20243,260,000 shares $641.57 million -8.2%2.3%2.7 $196.80 3/31/20243,550,000 shares $765.49 million +33.5%2.5%3 $215.63 3/15/20242,660,000 shares $583.36 million -5.0%1.8%2.4 $219.31 2/29/20242,800,000 shares $607.57 million -9.7%1.9%2.4 $216.99 2/15/20243,100,000 shares $692.39 million +1.3%2.2%2.8 $223.35 1/31/20243,060,000 shares $754.78 million -18.6%2.1%2.9 $246.66 1/15/20243,760,000 shares $932.93 million -3.8%2.6%3.4 $248.12 12/31/20233,910,000 shares $1.01 billion +32.5%2.7%3.6 $258.77 12/15/20232,950,000 shares $731.98 million +4.2%2.1%2.7 $248.13 11/30/20232,830,000 shares $662.45 million +7.6%2.0%2.9 $234.08 11/15/20232,630,000 shares $603.93 million -2.2%1.8%2.8 $229.63 10/31/20232,690,000 shares $638.98 million +1.9%1.9%3 $237.54 10/15/20232,640,000 shares $692.37 million -7.7%1.8%2.8 $262.26 9/30/20232,860,000 shares $735.05 million -10.9%2.0%3 $257.01 9/15/20233,210,000 shares $817.88 million +2.2%2.2%3.2 $254.79 8/31/20233,140,000 shares $839.51 million +3.6%2.2%2.9 $267.36 8/15/20233,030,000 shares $818.77 million -11.4%2.1%2.7 $270.22Get Your Bank Account “Fed Invasion” Ready with THESE 4 Simple Steps (Ad)Starting as soon as a few months from now, the United States government will make a sweeping change to bank accounts nationwide. It will give them unprecedented powers to control your bank account.Learn these 4 simple steps and protect your savings before it’s too late. 7/31/20233,420,000 shares $924.05 million +33.1%2.4%3.1 $270.19 7/15/20232,570,000 shares $716.85 million +24.2%1.8%2.2 $278.93 6/30/20232,070,000 shares $589.64 million -7.2%1.4%2 $284.85 6/15/20232,230,000 shares $664.16 million -11.9%1.6%2.3 $297.83 5/31/20232,530,000 shares $749.92 million -14.5%1.8%2.7 $296.41 5/15/20232,960,000 shares $923.14 million +30.4%2.1%3.3 $311.87 4/30/20232,270,000 shares $690.60 million +13.5%1.6%2.4 $304.23 4/15/20232,000,000 shares $576.26 million -2.4%1.4%2.4 $288.13 3/31/20232,050,000 shares $569.96 million +3.5%1.4%2.2 $278.03 3/15/20231,980,000 shares $519.49 million +7.0%1.4%2 $262.37 2/28/20231,850,000 shares $499.24 million +8.2%1.3%1.8 $269.86 2/15/20231,710,000 shares $477.06 million -8.6%1.2%1.5 $278.98 1/31/20231,870,000 shares $543.98 million -1.1%1.3%1.6 $290.90 1/15/20231,890,000 shares $544.40 million +10.5%1.3%1.5 $288.04 12/30/20221,710,000 shares $473.53 million -18.6%1.2%1.2 $276.92 12/15/20222,100,000 shares $595.22 million -15.7%1.5%1.2 $283.44 11/30/20222,490,000 shares $759.87 million +2.5%1.7%1.4 $305.17 11/15/20222,430,000 shares $728.47 million -1.6%N/A1.5 $299.78 10/31/20222,470,000 shares $700.10 million -1.2%1.7%1.6 $283.44 10/15/20222,500,000 shares $661.58 million -7.8%1.7%1.7 $264.63 9/30/20222,710,000 shares $723.57 million +30.9%1.9%2.1 $267.00 9/15/20222,070,000 shares $427.91 million +9.5%1.4%2.2 $206.72 8/31/20221,890,000 shares $369.27 million -5.5%1.3%2 $195.38 8/15/20222,000,000 shares $444.76 million +3.1%1.4%2.1 $222.38 7/31/20221,940,000 shares $417.22 million -7.2%1.3%1.8 $215.06 7/15/20222,090,000 shares $453.55 million -17.1%1.4%1.9 $217.01 6/30/20222,520,000 shares $513.93 million -5.3%1.7%2.3 $203.94 6/15/20222,660,000 shares $524.71 million +10.4%1.8%2.4 $197.26 5/31/20222,410,000 shares $482 million +9.6%1.7%2.2 $200.00 5/15/20222,200,000 shares $438.04 million +7.8%1.5%2 $199.11 4/30/20222,040,000 shares $423.18 million +5.7%1.4%1.9 $207.44 4/15/20221,930,000 shares $410.22 million No Change1.3%1.7 $212.55 3/31/20221,930,000 shares $406.46 million -12.3%1.3%1.4 $210.60 3/15/20222,200,000 shares $434.19 million -11.3%1.5%1.4 $197.36 2/28/20222,480,000 shares $523.30 million -2.4%1.7%1.6 $211.01 2/15/20222,540,000 shares $552.12 million -13.9%1.7%1.6 $217.37 1/31/20222,950,000 shares $666.70 million +2.1%2.0%1.8 $226.00 1/15/20222,890,000 shares $691.58 million +17.5%2.0%1.9 $239.30 12/31/20212,460,000 shares $590.20 million +5.6%1.7%1.8 $239.92 12/15/20212,330,000 shares $549.60 million -2.5%1.6%2 $235.88 11/30/20212,390,000 shares $563.42 million +16.6%1.6%2.1 $235.74 11/15/20212,050,000 shares $557.23 million -13.9%1.4%2 $271.82 10/29/20212,380,000 shares $634.70 million -0.8%1.6%2.3 $266.68 10/15/20212,400,000 shares $674.86 million -3.6%1.6%2.4 $281.19 9/30/20212,490,000 shares $704.65 million +2.1%1.7%2.4 $282.99 9/15/20212,440,000 shares $730.07 million +2.5%1.6%2.1 $299.21 8/31/20212,380,000 shares $806.61 million +9.2%1.6%1.7 $338.91 8/13/20212,180,000 shares $746.11 million +21.8%1.5%1.1 $342.25 7/30/20211,790,000 shares $584.85 million -4.3%1.2%0.9 $326.73 7/15/20211,870,000 shares $613.66 million -2.6%1.2%1 $328.16Get Your Bank Account “Fed Invasion” Ready with THESE 4 Simple Steps (Ad)Starting as soon as a few months from now, the United States government will make a sweeping change to bank accounts nationwide. It will give them unprecedented powers to control your bank account.Learn these 4 simple steps and protect your savings before it’s too late. 6/30/20211,920,000 shares $664.84 million -44.8%1.3%1 $346.27 6/15/20213,480,000 shares $1.38 billion +11.2%2.3%2 $396.08 5/28/20213,130,000 shares $837.21 million +3.0%2.1%1.9 $267.48 5/14/20213,040,000 shares $856.40 million -5.6%2.0%2.8 $281.71 4/30/20213,220,000 shares $854.36 million -0.6%2.1%2.9 $265.33 4/15/20213,240,000 shares $861.16 million -11.2%2.2%2.7 $265.79 3/31/20213,650,000 shares $1.01 billion -8.1%2.4%2.9 $276.01 3/15/20213,970,000 shares $1.06 billion +11.2%2.6%3 $266.13 2/26/20213,570,000 shares $989.82 million +4.4%2.4%2.8 $277.26 2/12/20213,420,000 shares $953.53 million -6.8%2.3%2.6 $278.81 1/29/20213,670,000 shares $983.08 million +0.8%2.4%2.4 $267.87 1/15/20213,640,000 shares $1.02 billion -2.4%2.4%2.1 $280.29 12/31/20203,730,000 shares $908.55 million -3.1%2.4%2.2 $243.58 12/15/20203,850,000 shares $944.21 million -7.0%2.5%2.3 $245.25 11/30/20204,140,000 shares $1.01 billion +11.6%2.7%2.5 $243.78 11/15/20203,710,000 shares $922.27 million -2.4%2.4%2.3 $248.59 10/30/20203,800,000 shares $932.82 million +26.3%2.5%2.5 $245.48 10/15/20203,010,000 shares $869.95 million +6.4%2.0%2.6 $289.02 9/30/20202,830,000 shares $802.81 million -23.3%1.8%2.5 $283.68 9/15/20203,690,000 shares $1.03 billion +11.5%2.3%3 $278.45 8/31/20203,310,000 shares $952.09 million +39.1%2.1%2.2 $287.64 8/14/20202,380,000 shares $688.89 million -6.7%1.5%1.6 $289.45 7/31/20202,550,000 shares $700.46 million -8.3%1.6%1.6 $274.69 7/15/20202,780,000 shares $781.93 million -14.7%1.8%1.7 $281.27 6/30/20203,260,000 shares $872.21 million -29.9%2.0%1.8 $267.55 6/15/20204,650,000 shares $1.29 billion +2.7%2.9%2.4 $278.49 5/29/20204,530,000 shares $1.39 billion +1.1%2.8%2.3 $307.09 5/15/20204,480,000 shares $1.42 billion +7.4%2.8%2.2 $316.60 4/30/20204,170,000 shares $1.24 billion +9.5%2.6%2 $296.83 4/15/20203,810,000 shares $1.25 billion +26.6%2.3%1.7 $326.94 BIIB Short Interest - Frequently Asked Questions What is Biogen's current short interest? Short interest is the volume of Biogen shares that have been sold short but have not yet been closed out or covered. As of March 31st, traders have sold 3,340,000 shares of BIIB short. 2.29% of Biogen's shares are currently sold short. Learn More on Biogen's current short interest. What is a good short interest ratio for Biogen? The short interest ratio, also known as the "days to cover ratio", is calculated by dividing the number of shares of a stock sold short divided by its average trading volume. A short interest ratio ranging between 1 and 4 generally indicates strong positive sentiment about a stock and a lack of short sellers. A short interest ratio of 10 or greater indicates strong pessimism about a stock. BIIB shares currently have a short interest ratio of 2.0. Learn More on Biogen's short interest ratio. Which institutional investors are shorting Biogen? As of the most recent reporting period, the following institutional investors, funds, and major shareholders have reported short positions of Biogen: GTS Securities LLC, Wolverine Trading LLC, Squarepoint Ops LLC, Royal Bank of Canada, Nomura Holdings Inc., Millennium Management LLC, Group One Trading LLC, Eisler Capital Management Ltd., D. E. Shaw & Co. Inc., Cubist Systematic Strategies LLC, Caption Management LLC, Capstone Investment Advisors LLC, Citadel Advisors LLC, Bank of America Corp DE, Jane Street Group LLC, Tudor Investment Corp ET AL, Susquehanna International Group LLP, Concourse Financial Group Securities Inc., Walleye Trading LLC, Walleye Capital LLC, Barclays PLC, Capital Fund Management S.A., JPMorgan Chase & Co., Mirae Asset Securities USA Inc., Simplex Trading LLC, Twin Tree Management LP, and SG Americas Securities LLC. These positions are disclosed in Form 13F filings with the Securities and Exchange Commission. What is a good short interest percentage for Biogen? Companies that have a short interest as a percentage of float below 10% indicates positive investor sentiment and few short sellers. Stocks with a short interest percentage above 10% is considered high, suggesting some investors are pessimistic about the stock. Companies with a short interest percentage of 20% or more indicates widespread negative sentiment. 2.29% of Biogen's floating shares are currently sold short. Is Biogen's short interest increasing or decreasing? Biogen saw a increase in short interest during the month of March. As of March 31st, there was short interest totaling 3,340,000 shares, an increase of 0.9% from the previous total of 3,310,000 shares. Changes in short volume can be used to identify positive and negative investor sentiment. Investors that short sell a stock are betting that its price will decline in the future. An increase in short sale volume suggests bearish (negative) sentiment among investors. A decrease on short sale volume suggests bullish (positive) sentiment. What is Biogen's float size? Biogen currently has issued a total of 146,375,000 shares. Some of Biogen's outstanding shares are available for trading, while others are subject to various restrictions. The public float, also referred to as floating shares or "the float", are shares that publicly owned, unrestricted and available to trade on the open market. Biogen currently has a public float of 145,630,000 shares. How does Biogen's short interest compare to its competitors? 2.29% of Biogen's shares are currently sold short. Here is how the short interest of companies in the industry of "biotechnology" compare to Biogen: Regeneron Pharmaceuticals, Inc. (2.76%), Alnylam Pharmaceuticals, Inc. (2.34%), United Therapeutics Co. (3.88%), Incyte Co. (3.77%), BioMarin Pharmaceutical Inc. (2.51%), Exelixis, Inc. (5.49%), Neurocrine Biosciences, Inc. (3.97%), Exact Sciences Co. (6.12%), Halozyme Therapeutics, Inc. (7.54%), Madrigal Pharmaceuticals, Inc. (23.76%), Which stocks are the most shorted right now? As of the most recent reporting period, the following stocks had the largest short interest positions: Invesco QQQ ($21.93 billion), iShares 20+ Year Treasury Bond ETF ($9.31 billion), Strategy Incorporated ($8.42 billion), Charter Communications, Inc. ($4.52 billion), Apollo Global Management, Inc. ($4.26 billion), Super Micro Computer, Inc. ($3.98 billion), Capital One Financial Co. ($3.79 billion), TC Energy Co. ($3.43 billion), AppLovin Co. ($2.91 billion), and Schlumberger Limited ($2.89 billion). View all of the most shorted stocks. What does it mean to sell short Biogen stock? Short selling BIIB is an investing strategy that aims to generate trading profit from Biogen as its price is falling. BIIB shares are trading up $2.79 today. To short a stock, an investor borrows shares, sells them and buys the shares back on the public market later to return it to the lender. Short sellers are betting that a stock will decline in price. If the stock does drop after selling, the short seller buys it back at a lower price and returns it to the lender. The difference between the sell price and the buy price is the trader's profit. How does a short squeeze work against Biogen? A short squeeze for Biogen occurs when it has a large amount of short interest and its stock increases in price. This forces short sellers to cover their short interest positions by buying actual shares of BIIB, which in turn drives the price of the stock up even further. How often is Biogen's short interest reported? Short interest is typically published by a stock exchange once per month. However, NASDAQ publishes a report for U.S. stocks, including BIIB, twice per month. The most recent reporting period available is March, 31 2025. More Short Interest Resources from MarketBeat Related Companies Regeneron Pharmaceuticals Short Interest Data Alnylam Pharmaceuticals Short Interest Data United Therapeutics Short Interest Data Incyte Short Interest Data BioMarin Pharmaceutical Short Interest Data Exelixis Short Interest Data Neurocrine Biosciences Short Interest Data Exact Sciences Short Interest Data Halozyme Therapeutics Short Interest Data Madrigal Pharmaceuticals Short Interest Data Short Interest Tools Stocks to Short Largest Short Interest Positions Short Interest Increases Short Interest Decreases Short Interest Reporting Dates This page (NASDAQ:BIIB) was last updated on 4/15/2025 by MarketBeat.com Staff From Our Partners[Action Required] Claim Your FREE IRS Loophole GuideThis shouldn't surprise anyone who's been paying attention, but... Pres. 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