Spero Therapeutics (SPRO) Short Interest Ratio & Short Volume $2.30 -0.02 (-0.86%) Closing price 08/1/2025 04:00 PM EasternExtended Trading$2.31 +0.01 (+0.61%) As of 08/1/2025 05:00 PM Eastern Extended trading is trading that happens on electronic markets outside of regular trading hours. This is a fair market value extended hours price provided by Polygon.io. Learn more. Add Compare Share Share Short Interest Stock AnalysisAnalyst ForecastsChartCompetitorsEarningsFDA EventsHeadlinesInsider TradesOptions ChainOwnershipSEC FilingsShort InterestSustainabilityTrendsBuy This Stock Spero Therapeutics Short Interest DataSpero Therapeutics (SPRO) has a short interest of 1.22 million shares. This marks a -28.24% decrease in short interest from the previous month. The short interest ratio (days to cover) is 0.3, indicating that it would take 0.3 days of the average trading volume of 770,756 shares to cover all short positions.Current Short Interest1,220,000 sharesPrevious Short Interest1,700,000 sharesChange Vs. Previous Month-28.24%Dollar Volume Sold Short$3.04 millionShort Interest Ratio0.3 Days to CoverLast Record DateJuly 15, 2025Outstanding Shares55,910,000 sharesPercentage of Shares Shorted2.18%Today's Trading Volume518,730 sharesAverage Trading Volume770,756 sharesToday's Volume Vs. Average67% Short Selling Spero Therapeutics? Sign up to receive the latest short interest report for Spero Therapeutics and its competitors with MarketBeat's FREE newsletter. Email Address Skip Charts & View Short Interest HistoryShort Interest ChartDays to Cover ChartShort Percent of Float ChartSPRO Short Interest Over TimeSPRO Days to Cover Over TimeSPRO Percentage of Float Shorted Over Time Spero Therapeutics Short Interest History Export to ExcelReport DateTotal Shares Sold ShortDollar Volume Sold ShortChange from Previous ReportPercentage of Float ShortedDays to CoverPrice on Report Date 7/15/20251,220,000 shares $3.04 million -28.2%N/A0.3 $2.49 6/30/20251,700,000 shares $4.93 million +5.6%3.2%0.4 $2.90 6/15/20251,610,000 shares $4.56 million -53.7%3.0%0.4 $2.83 5/31/20253,480,000 shares $8.98 million +446.6%6.7%0.9 $2.58 5/15/2025636,700 shares $414.62 thousand -1.3%1.2%5 $0.65 4/30/2025645,200 shares $424.54 thousand -19.5%N/A5 $0.66 4/15/2025801,300 shares $596.49 thousand +60.9%1.5%4.8 $0.74 3/31/2025498,100 shares $358.63 thousand +13.9%1.0%2.6 $0.72 3/15/2025437,300 shares $342.14 thousand +3.0%0.8%2.2 $0.78 2/28/2025424,700 shares $329.40 thousand -1.1%0.8%2 $0.78 Get the Latest News and Ratings for SPRO and Related StocksEnter your email address below to receive the latest news and analysts' ratings for Spero Therapeutics and its competitors with MarketBeat's FREE daily newsletter. 2/15/2025429,600 shares $350.12 thousand +14.0%0.8%1.9 $0.82 1/31/2025376,800 shares $322.77 thousand +6.4%N/A1.5 $0.86 1/15/2025354,100 shares $317.70 thousand -14.2%N/A1.2 $0.90 12/31/2024412,600 shares $424.98 thousand -8.6%N/A1.4 $1.03 12/15/2024451,200 shares $482.78 thousand -8.6%N/A1.7 $1.07 11/30/2024493,800 shares $562.93 thousand -9.7%N/A2 $1.14 11/15/2024546,800 shares $645.22 thousand -12.5%N/A2.3 $1.18 10/31/2024625,200 shares $769.00 thousand +61.5%N/A3 $1.23 10/15/2024387,100 shares $464.52 thousand +0.7%N/A3.2 $1.20 9/30/2024384,300 shares $514.96 thousand -0.2%N/A3 $1.34 9/15/2024385,200 shares $527.72 thousand -5.8%N/A3.4 $1.37 8/31/2024409,100 shares $560.47 thousand +8.6%N/A3.1 $1.37 8/15/2024376,700 shares $455.81 thousand +5.8%N/A2.9 $1.21 7/31/2024355,900 shares $501.82 thousand -8.8%N/A2.6 $1.41 7/15/2024390,300 shares $563.98 thousand -7.1%N/A2.7 $1.45 6/30/2024420,000 shares $546 thousand -3.3%N/A2.5 $1.30 6/15/2024434,200 shares $590.51 thousand -10.3%N/A2.3 $1.36 5/31/2024483,900 shares $687.14 thousand -2.1%N/A1.7 $1.42 5/15/2024494,200 shares $800.60 thousand +5.6%N/A1.6 $1.62 4/30/2024468,100 shares $664.70 thousand -8.8%N/A1.5 $1.42 4/15/2024513,200 shares $785.20 thousand -21.5%N/A1.6 $1.53 3/31/2024653,800 shares $1.12 million +6.5%N/A2.1 $1.72 3/15/2024613,900 shares $1.10 million +8.9%N/A2 $1.79 2/29/2024564,000 shares $930.60 thousand -8.9%N/A2.8 $1.65 2/15/2024619,000 shares $940.88 thousand -12.5%N/A3.2 $1.52 1/31/2024707,100 shares $1.07 million +4.0%N/A3.8 $1.52 1/15/2024680,200 shares $986.29 thousand -13.8%N/A4 $1.45 12/31/2023789,000 shares $1.16 million -19.2%N/A4.5 $1.47 12/15/2023976,500 shares $1.26 million -9.6%N/A6 $1.29 11/30/20231,080,000 shares $1.23 million -4.4%N/A6.2 $1.14Elon’s BIGGEST warning yet? (Ad)Tesla's About to Prove Everyone Wrong... Again Back in 2018, when Jeff Brown told everyone to buy Tesla… The "experts" said Elon was finished and Tesla was headed for bankruptcy. Now they're saying the same thing, but Jeff has uncovered Tesla's next breakthrough.Click here to see why Tesla's about to prove everyone wrong... again. 11/15/20231,130,000 shares $1.29 million -10.3%N/A4.7 $1.14 10/31/20231,260,000 shares $1.36 million -3.1%N/A4.8 $1.08 10/15/20231,300,000 shares $1.47 million -3.7%N/A4.1 $1.13 9/30/20231,350,000 shares $1.63 million -5.6%N/A4.2 $1.21 9/15/20231,430,000 shares $1.83 million +25.4%N/A4.3 $1.28 8/31/20231,140,000 shares $1.71 million No ChangeN/A3.2 $1.50 8/15/20231,140,000 shares $1.53 million -2.6%N/A3.8 $1.35 7/31/20231,170,000 shares $1.91 million No ChangeN/A3.9 $1.63 7/15/20231,170,000 shares $1.77 million -4.9%N/A4.2 $1.51 6/30/20231,230,000 shares $1.78 million +40.4%N/A4 $1.45 6/15/2023876,300 shares $1.38 million -0.6%N/A1.8 $1.57 5/31/2023881,800 shares $1.53 million -9.5%N/A1.7 $1.74 5/15/2023974,400 shares $1.82 million -32.8%N/A1.7 $1.87 4/30/20231,450,000 shares $2.57 million -21.6%N/A2.5 $1.77 4/15/20231,850,000 shares $3.18 million +17.1%N/A3.3 $1.72 3/31/20231,580,000 shares $2.29 million +67.6%N/A2.8 $1.45 3/15/2023942,700 shares $1.39 million +142.0%N/A2.1 $1.47 2/28/2023389,500 shares $576.46 thousand +35.5%N/A0.9 $1.48 2/15/2023287,400 shares $514.45 thousand -38.6%N/A0.7 $1.79 1/31/2023468,200 shares $866.17 thousand -29.9%N/A0.8 $1.85 1/15/2023667,900 shares $1.34 million -21.4%N/A1.1 $2.00 12/30/2022849,400 shares $1.47 million -14.6%N/A1.1 $1.73 12/15/2022994,200 shares $1.69 million -23.5%N/A0.4 $1.70 11/30/20221,300,000 shares $2.52 million -13.9%N/A0.2 $1.94 11/15/20221,510,000 shares $2.84 million +22.8%5.5%0.2 $1.88 10/31/20221,230,000 shares $2.41 million -15.8%4.5%0.2 $1.96 10/15/20221,460,000 shares $2.89 million -32.4%5.4%0.2 $1.98 9/30/20222,160,000 shares $4.32 million +177.9%8.0%0.3 $2.00 9/15/2022777,200 shares $753.88 thousand +182.0%2.9%0.1 $0.97 8/31/2022275,600 shares $222.38 thousand -32.9%1.0%0.1 $0.81 8/15/2022410,600 shares $371.06 thousand +1.1%1.5%1.3 $0.90 7/31/2022406,100 shares $297.35 thousand -27.2%1.6%1.1 $0.73 7/15/2022557,800 shares $440.66 thousand +34.9%2.3%0.8 $0.79 6/30/2022413,600 shares $306.48 thousand -70.9%1.7%0.6 $0.74 6/15/20221,420,000 shares $1.36 million -9.0%5.8%1.9 $0.96 5/31/20221,560,000 shares $1.84 million -5.5%6.4%2.3 $1.18 5/15/20221,650,000 shares $2.82 million -55.3%6.8%2.6 $1.71 4/30/20223,690,000 shares $17.93 million +6.7%14.6%6.3 $4.86 4/15/20223,460,000 shares $21.14 million +6.5%13.7%16.7 $6.11 3/31/20223,250,000 shares $28.28 million +4.2%13.1%16.5 $8.70 3/15/20223,120,000 shares $25.40 million +5.4%12.6%18.6 $8.14 2/28/20222,960,000 shares $28.42 million +5.7%11.9%20.8 $9.60 2/15/20222,800,000 shares $27.94 million +12.0%11.3%19.6 $9.98 1/31/20222,500,000 shares $29.68 million +4.6%10.1%18.6 $11.87 1/15/20222,390,000 shares $31.55 million +4.4%9.4%21.1 $13.20 12/31/20212,290,000 shares $36.66 million -1.7%9.0%23.2 $16.01 12/15/20212,330,000 shares $30.64 million -0.9%9.2%24.5 $13.15 11/30/20212,350,000 shares $33.49 million -2.5%9.3%23.9 $14.25 11/15/20212,410,000 shares $39.55 million -3.6%9.5%22.4 $16.41 10/29/20212,500,000 shares $43.90 million No Change9.9%21 $17.56Elon’s BIGGEST warning yet? (Ad)Tesla's About to Prove Everyone Wrong... Again Back in 2018, when Jeff Brown told everyone to buy Tesla… The "experts" said Elon was finished and Tesla was headed for bankruptcy. Now they're saying the same thing, but Jeff has uncovered Tesla's next breakthrough.Click here to see why Tesla's about to prove everyone wrong... again. 10/15/20212,500,000 shares $42.55 million -1.2%9.9%21.4 $17.02 9/30/20212,530,000 shares $46.58 million -1.9%10.0%20.4 $18.41 9/15/20212,580,000 shares $47.81 million -4.1%10.2%16.4 $18.53 8/31/20212,690,000 shares $51.78 million +1.9%10.9%15.8 $19.25 8/13/20212,640,000 shares $35.69 million No Change10.7%16.5 $13.52 7/30/20212,640,000 shares $35.22 million No Change11.6%17 $13.34 7/15/20212,640,000 shares $37.73 million +10.0%12.1%16.6 $14.29 6/30/20212,400,000 shares $33.50 million -23.1%9.9%14.5 $13.96 6/15/20213,120,000 shares $47.55 million -1.0%12.9%22.1 $15.24 5/28/20213,150,000 shares $45.68 million -3.4%13.0%20.3 $14.50 5/14/20213,260,000 shares $42.28 million -2.1%N/A19.9 $12.97 4/30/20213,330,000 shares $45.59 million -2.1%N/A17.5 $13.69 4/15/20213,400,000 shares $44.81 million +0.6%N/A14 $13.18 3/31/20213,380,000 shares $46.04 million +50.9%N/A12.9 $13.62 3/15/20212,240,000 shares $37.50 million +1.8%N/A6.7 $16.74 2/26/20212,200,000 shares $40.44 million -1.8%N/A6.6 $18.38 2/12/20212,240,000 shares $45.52 million -0.4%N/A6.6 $20.32 1/29/20212,250,000 shares $40.95 million +0.9%N/A6.4 $18.20 1/15/20212,230,000 shares $37.08 million -0.9%N/A7.3 $16.63 12/31/20202,250,000 shares $45.52 million +17.8%N/A7.3 $20.23 12/15/20201,910,000 shares $34.02 million -2.1%N/A6.2 $17.81 11/30/20201,950,000 shares $32.62 million +1.6%N/A5.9 $16.73 11/15/20201,920,000 shares $27.49 million +2.7%N/A5 $14.32 10/30/20201,870,000 shares $25.13 million +3.3%N/A5.1 $13.44 10/15/20201,810,000 shares $24.63 million +1.7%N/A5.2 $13.61 9/30/20201,780,000 shares $19.86 million -6.3%N/A5.4 $11.16 9/15/20201,900,000 shares $18.98 million +49.6%N/A6.4 $9.99 8/31/20201,270,000 shares $13.80 million +18.7%8.5%5.3 $10.87 8/14/20201,070,000 shares $13.38 million +2.9%7.2%6.7 $12.50 SPRO Short Interest - Frequently Asked Questions What is Spero Therapeutics' current short interest? Short interest is the volume of Spero Therapeutics shares that have been sold short but have not yet been closed out or covered. As of July 15th, investors have sold 1,220,000 shares of SPRO short. Learn More on Spero Therapeutics' current short interest. Which institutional investors are shorting Spero Therapeutics? As of the most recent reporting period, the following institutional investors, funds, and major shareholders have reported short positions of Spero Therapeutics: Simplex Trading LLC. These positions are disclosed in Form 13F filings with the Securities and Exchange Commission. Is Spero Therapeutics' short interest increasing or decreasing? Spero Therapeutics saw a decrease in short interest during the month of July. As of July 15th, there was short interest totaling 1,220,000 shares, a decrease of 28.2% from the previous total of 1,700,000 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. How does Spero Therapeutics' short interest compare to its competitors? Here is how the short interest of companies in the industry of "pharmaceutical products" compare to Spero Therapeutics: aTyr Pharma, Inc. (23.68%), Siga Technologies Inc. (6.83%), Tourmaline Bio, Inc. (18.39%), Erasca, Inc. (12.31%), Cullinan Therapeutics, Inc. (16.37%), Kodiak Sciences Inc. (5.12%), Precigen, Inc. (19.44%), PureTech Health PLC Sponsored ADR (0.02%), REGENXBIO Inc. (12.32%), Savara Inc. (25.67%), Which stocks are the most shorted right now? As of the most recent reporting period, the following stocks had the largest short interest positions: Coinbase Global, Inc. ($5.11 billion), Charter Communications, Inc. ($4.76 billion), Reddit Inc. ($2.84 billion), SoFi Technologies, Inc. ($2.79 billion), Seagate Technology Holdings PLC ($2.79 billion), Live Nation Entertainment, Inc. ($2.67 billion), Rocket Lab Corporation ($2.49 billion), AST SpaceMobile, Inc. ($2.12 billion), Moderna, Inc. ($2.09 billion), and Omnicom Group Inc. ($2.04 billion). View all of the most shorted stocks. What does it mean to sell short Spero Therapeutics stock? Short selling SPRO is an investing strategy that aims to generate trading profit from Spero Therapeutics as its price is falling. SPRO shares are trading down $0.02 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 Spero Therapeutics? A short squeeze for Spero Therapeutics 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 SPRO, which in turn drives the price of the stock up even further. How often is Spero Therapeutics' 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 SPRO, twice per month. The most recent reporting period available is July, 15 2025. More Short Interest Resources from MarketBeat Related Companies aTyr Pharma Short Interest Siga Technologies Short Interest Tourmaline Bio Short Interest Erasca Short Interest Cullinan Therapeutics Short Interest Kodiak Sciences Short Interest Precigen Short Interest PureTech Health Short Interest REGENXBIO Short Interest Savara Short Interest Short Interest Tools Stocks to Short Largest Short Interest Positions Short Interest Increases Short Interest Decreases Short Interest Reporting Dates This page (NASDAQ:SPRO) was last updated on 8/2/2025 by MarketBeat.com Staff From Our PartnersElon’s Secret Social Security BombshellTo All Americans Born Before April 16th, 1963: Did Trump Just Give The Green Light To Radically RE-DO Social S...Banyan Hill Publishing | SponsoredElon’s BIGGEST warning yet?Tesla's About to Prove Everyone Wrong... 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