Castle Biosciences (CSTL) Short Interest Ratio & Short Volume $19.94 -0.16 (-0.80%) Closing price 04:00 PM EasternExtended Trading$19.93 -0.01 (-0.05%) As of 04:05 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 ForecastsChartCompetitorsEarningsFinancialsHeadlinesInsider TradesOptions ChainOwnershipSEC FilingsShort InterestTrendsBuy This Stock Castle Biosciences Short Interest DataCastle Biosciences (CSTL) has a short interest of 1.76 million shares, representing 6.77% of the float (the number of shares available for trading by the public). This marks a -4.86% decrease in short interest from the previous month. The short interest ratio (days to cover) is 4.0, indicating that it would take 4.0 days of the average trading volume of 369,865 shares to cover all short positions.Current Short Interest1,760,000 sharesPrevious Short Interest1,850,000 sharesChange Vs. Previous Month-4.86%Dollar Volume Sold Short$33.95 millionShort Interest Ratio4.0 Days to CoverLast Record DateMarch 15, 2025Outstanding Shares28,007,000 sharesShort Percent of Float6.77%Today's Trading Volume203,414 sharesAverage Trading Volume369,865 sharesToday's Volume Vs. Average55% Short Selling Castle Biosciences? Sign up to receive the latest short interest report for Castle Biosciences and its competitors with MarketBeat's FREE newsletter. Email Address Skip Charts & View Short Interest HistoryShort Interest ChartDays to Cover ChartShort Percent of Float ChartCSTL Short Interest Over TimeCSTL Days to Cover Over TimeCSTL Percentage of Float Shorted Over Time Remove Ads Castle Biosciences Short Interest History Export to ExcelReport DateTotal Shares Sold ShortDollar Volume Sold ShortChange from Previous ReportPercentage of Float ShortedDays to CoverPrice on Report Date 3/15/20251,760,000 shares $33.95 million -4.9%6.8%4 $19.29 2/28/20251,850,000 shares $40.11 million -4.2%7.1%4.4 $21.68 2/15/20251,930,000 shares $52.73 million +12.9%7.4%5.1 $27.32 1/31/20251,710,000 shares $48.34 million +2.4%N/A4.5 $28.27 1/15/20251,670,000 shares $41.78 million +1.2%N/A4.1 $25.02 12/31/20241,650,000 shares $43.97 million -1.8%N/A4.2 $26.65 12/15/20241,680,000 shares $48.50 million -8.7%N/A4.5 $28.87 11/30/20241,840,000 shares $55.72 million +7.6%N/A4.7 $30.28 11/15/20241,710,000 shares $48.05 million +6.2%N/A4.4 $28.10 10/31/20241,610,000 shares $55.82 million -8.0%N/A4.1 $34.67 Get the Latest News and Ratings for CSTL and Related StocksEnter your email address below to receive the latest news and analysts' ratings for Castle Biosciences and its competitors with MarketBeat's FREE daily newsletter. 10/15/20241,750,000 shares $58.59 million +8.7%N/A4.2 $33.48 9/30/20241,610,000 shares $45.92 million -6.4%N/A4.1 $28.52 9/15/20241,720,000 shares $53.63 million -2.8%N/A4.1 $31.18 8/31/20241,770,000 shares $52.52 million +4.1%N/A4.4 $29.67 8/15/20241,700,000 shares $46.14 million +21.4%N/A4.3 $27.14 7/31/20241,400,000 shares $33.78 million -22.7%N/A3.8 $24.13 7/15/20241,810,000 shares $34.12 million +54.7%N/A5.9 $18.85 6/30/20241,170,000 shares $25.47 million +2.6%N/A4.3 $21.77 6/15/20241,140,000 shares $26.13 million -0.9%N/A4.9 $22.92 5/31/20241,150,000 shares $26.75 million -10.9%N/A5.1 $23.26 5/15/20241,290,000 shares $31.42 million -10.4%N/A5 $24.36 4/30/20241,440,000 shares $30.37 million -1.4%N/A5.8 $21.09 4/15/20241,460,000 shares $28.08 million +2.1%N/A6.3 $19.23 3/31/20241,430,000 shares $31.67 million +0.7%N/A5.7 $22.15 3/15/20241,420,000 shares $26.77 million +17.4%N/A5.6 $18.85 2/29/20241,210,000 shares $21.85 million -3.2%N/A4.6 $18.06 2/15/20241,250,000 shares $31.10 million +0.8%5.0%5.5 $24.88 1/31/20241,240,000 shares $28.62 million +29.3%5.0%5.4 $23.08 1/15/2024958,800 shares $19.20 million +19.8%3.8%3.7 $20.03 12/31/2023800,300 shares $17.27 million -18.1%3.2%2.9 $21.58 12/15/2023977,300 shares $19.61 million -17.2%3.9%3.6 $20.07 11/30/20231,180,000 shares $23.59 million -9.2%4.7%4.7 $19.99 11/15/20231,300,000 shares $24.99 million -9.1%5.2%5.2 $19.22 10/31/20231,430,000 shares $22.34 million +28.8%N/A5.6 $15.62 10/15/20231,110,000 shares $13.74 million +11.6%N/A4 $12.38 9/30/2023994,800 shares $16.80 million +19.4%N/A3 $16.89 9/15/2023833,200 shares $14.41 million +16.2%N/A1.5 $17.30 8/31/2023716,800 shares $14.29 million -3.6%N/A1.1 $19.93 8/15/2023743,500 shares $13.97 million -14.1%N/A0.9 $18.79 7/31/2023865,500 shares $14.58 million +1.3%N/A1 $16.85Trump’s Bitcoin Reserve is No Accident… (Ad)Bryce Paul believes this is the #1 coin to buy right now The catalyst behind this surge is a massive new blockchain development…Just click here to get all the details on this crypto coin now 7/15/2023854,500 shares $13.63 million +32.2%N/A1.1 $15.95 6/30/2023646,400 shares $8.87 million -26.8%N/A0.9 $13.72 6/15/2023883,200 shares $11.83 million +16.4%N/A2 $13.40 5/31/2023758,600 shares $18.53 million -13.6%N/A2 $24.43 5/15/2023878,100 shares $20.69 million -11.0%N/A6 $23.56 4/30/2023986,400 shares $22.32 million +0.7%N/A6.9 $22.63 4/15/2023979,400 shares $22.11 million -4.9%N/A6.8 $22.58 3/31/20231,030,000 shares $23.40 million -2.8%N/A7.1 $22.72 3/15/20231,060,000 shares $24.01 million +23.0%N/A6.8 $22.65 2/28/2023862,000 shares $21.71 million -25.0%N/A5.6 $25.18 2/15/20231,150,000 shares $30.94 million +4.6%N/A7.8 $26.90 1/31/20231,100,000 shares $29.79 million -2.7%N/A6.4 $27.08 1/15/20231,130,000 shares $30.75 million -5.0%N/A6 $27.21 12/30/20221,190,000 shares $28.01 million +5.3%4.9%5.9 $23.54 12/15/20221,130,000 shares $27.90 million +5.6%4.6%5.6 $24.69 11/30/20221,070,000 shares $25.24 million +0.9%4.4%5.3 $23.59 11/15/20221,060,000 shares $24.41 million -9.4%4.3%5.3 $23.03 10/31/20221,170,000 shares $29.86 million -10.0%4.8%5.9 $25.52 10/15/20221,300,000 shares $28.63 million +4.0%5.3%6.6 $22.02 9/30/20221,250,000 shares $32.60 million +7.8%5.3%6.3 $26.08 9/15/20221,160,000 shares $32.97 million -1.7%4.9%4.9 $28.42 8/31/20221,180,000 shares $34.22 million -1.7%5.0%4.5 $29.00 8/15/20221,200,000 shares $40.19 million -17.2%5.1%4.1 $33.49 7/31/20221,450,000 shares $40.54 million +10.7%6.1%4.5 $27.96 7/15/20221,310,000 shares $32.40 million -1.5%5.4%3.6 $24.73 6/30/20221,330,000 shares $29.19 million +1.5%5.5%3.1 $21.95 6/15/20221,310,000 shares $22.22 million +3.2%5.4%3.2 $16.96 5/31/20221,270,000 shares $28.28 million -1.6%5.4%3.6 $22.27 5/15/20221,290,000 shares $25.43 million -2.3%5.5%3.9 $19.71 4/30/20221,320,000 shares $29.49 million +8.2%5.8%4.3 $22.34 4/15/20221,220,000 shares $31.65 million -9.6%5.3%4.1 $25.94 3/31/20221,350,000 shares $60.56 million -6.9%5.9%6.2 $44.86 3/15/20221,450,000 shares $52.87 million -4.6%6.3%6.8 $36.46 2/28/20221,520,000 shares $65.80 million +4.1%6.7%6.6 $43.29 2/15/20221,460,000 shares $62.78 million +3.6%6.4%5.8 $43.00 1/31/20221,410,000 shares $60.98 million +19.5%6.2%5.3 $43.25 1/15/20221,180,000 shares $43.29 million +22.6%6.5%4.9 $36.69 12/31/2021962,800 shares $41.28 million -12.5%5.4%4.3 $42.87 12/15/20211,100,000 shares $45.44 million +5.8%6.2%5 $41.31 11/30/20211,040,000 shares $42.98 million +24.5%5.8%4.9 $41.33 11/15/2021835,200 shares $43.76 million -1.3%4.7%4.5 $52.40 10/29/2021846,200 shares $52.76 million -14.8%4.8%5 $62.35 10/15/2021992,900 shares $63.13 million -16.6%5.6%6.3 $63.58 9/30/20211,190,000 shares $79.14 million -4.0%6.7%7.5 $66.50 9/15/20211,240,000 shares $92.65 million -12.1%7.0%7 $74.72 8/31/20211,410,000 shares $108.19 million No Change8.0%7.5 $76.73 8/13/20211,410,000 shares $90.86 million +1.4%8.0%6.9 $64.44 7/30/20211,390,000 shares $97.09 million -6.7%7.9%6 $69.85 7/15/20211,490,000 shares $96.76 million -3.3%8.5%6.1 $64.94 6/30/20211,540,000 shares $112.93 million +14.9%8.8%6.1 $73.33Trump’s Bitcoin Reserve is No Accident… (Ad)Bryce Paul believes this is the #1 coin to buy right now The catalyst behind this surge is a massive new blockchain development…Just click here to get all the details on this crypto coin now 6/15/20211,340,000 shares $97.27 million -1.5%7.7%5.2 $72.59 5/28/20211,360,000 shares $81.50 million +8.8%7.8%4.8 $59.93 5/14/20211,250,000 shares $62.59 million -44.2%N/A4 $50.07 4/30/20212,240,000 shares $152.48 million +1.8%14.6%7.3 $68.07 4/15/20212,200,000 shares $150.79 million -7.2%14.3%7.1 $68.54 3/31/20212,370,000 shares $147.37 million +0.9%15.5%7.4 $62.18 3/15/20212,350,000 shares $150.85 million +54.6%N/A7.2 $64.19 2/26/20211,520,000 shares $113.22 million +7.0%N/A4.3 $74.49 2/12/20211,420,000 shares $133.76 million -4.1%N/A4.4 $94.20 1/29/20211,480,000 shares $101.39 million -2.6%9.3%4.6 $68.51 1/15/20211,520,000 shares $114.94 million -9.0%9.6%5.2 $75.62 12/31/20201,670,000 shares $114.91 million +44.0%11.3%6.1 $68.81 12/15/20201,160,000 shares $71.83 million -2.5%7.9%4.5 $61.92 11/30/20201,190,000 shares $52.92 million -4.0%8.4%6.2 $44.47 11/15/20201,240,000 shares $62.45 million -1.6%8.9%6.8 $50.36 10/30/20201,260,000 shares $59.36 million +22.3%9.1%7 $47.11 10/15/20201,030,000 shares $54.37 million +40.4%7.5%5.9 $52.79 9/30/2020733,800 shares $37.75 million +40.3%5.4%4.2 $51.45 9/15/2020522,900 shares $25.35 million -23.5%3.9%2.5 $48.48 8/31/2020683,200 shares $31.24 million -18.1%5.1%3.1 $45.73 8/14/2020834,000 shares $34.46 million -5.1%6.5%4 $41.32 7/31/2020879,200 shares $34.04 million -6.5%7.0%3.9 $38.72 7/15/2020939,800 shares $40.38 million -15.3%7.6%4.1 $42.97 6/30/20201,110,000 shares $41.84 million -12.6%9.6%4.9 $37.69 6/15/20201,270,000 shares $47.02 million -1.6%13.0%6.7 $37.02 5/29/20201,290,000 shares $49.57 million +13.2%13.3%7 $38.43 5/15/20201,140,000 shares $40.36 million +17.0%12.0%6.1 $35.40 4/30/2020974,800 shares $29.73 million +12.2%10.3%6 $30.50 4/15/2020868,800 shares $25.79 million +1.9%9.2%5.5 $29.69 3/31/2020852,300 shares $25.10 million +35.8%9.0%5.4 $29.45 CSTL Short Interest - Frequently Asked Questions What is Castle Biosciences' current short interest? Short interest is the volume of Castle Biosciences shares that have been sold short but have not yet been closed out or covered. As of March 15th, investors have sold 1,760,000 shares of CSTL short. 6.77% of Castle Biosciences' shares are currently sold short. Learn More on Castle Biosciences' current short interest. What is a good short interest ratio for Castle Biosciences? 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. CSTL shares currently have a short interest ratio of 4.0. Learn More on Castle Biosciences's short interest ratio. Which institutional investors are shorting Castle Biosciences? As of the most recent reporting period, the following institutional investors, funds, and major shareholders have reported short positions of Castle Biosciences: Wolverine Trading LLC, Torno Capital LLC, Group One Trading LLC, Citadel Advisors LLC, and Concourse Financial Group Securities Inc.. These positions are disclosed in Form 13F filings with the Securities and Exchange Commission. What is a good short interest percentage for Castle Biosciences? 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. 6.77% of Castle Biosciences' floating shares are currently sold short. Is Castle Biosciences' short interest increasing or decreasing? Castle Biosciences saw a drop in short interest in March. As of March 15th, there was short interest totaling 1,760,000 shares, a drop of 4.9% from the previous total of 1,850,000 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 Castle Biosciences' short interest compare to its competitors? 6.77% of Castle Biosciences' shares are currently sold short. Here is how the short interest of companies in the industry of "healthcare" compare to Castle Biosciences: Progyny, Inc. (14.25%), agilon health, inc. (6.11%), PACS Group, Inc. (5.72%), Addus HomeCare Co. (3.78%), Teladoc Health, Inc. (15.73%), AdaptHealth Corp. (11.07%), Viridian Therapeutics, Inc. (12.71%), Grail, Inc. (12.61%), Aveanna Healthcare Holdings Inc. (2.71%), CareDx, Inc (11.05%), 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 ($26.28 billion), iShares 20+ Year Treasury Bond ETF ($9.53 billion), MicroStrategy Incorporated ($8.50 billion), Apollo Global Management, Inc. ($4.86 billion), Super Micro Computer, Inc. ($4.85 billion), Charter Communications, Inc. ($4.28 billion), Capital One Financial Co. ($4.08 billion), AppLovin Co. ($3.82 billion), Canadian Natural Resources Limited ($3.78 billion), and Schlumberger Limited ($2.87 billion). View all of the most shorted stocks. What does it mean to sell short Castle Biosciences stock? Short selling CSTL is an investing strategy that aims to generate trading profit from Castle Biosciences as its price is falling. CSTL shares are trading down $0.16 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 Castle Biosciences? A short squeeze for Castle Biosciences 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 CSTL, which in turn drives the price of the stock up even further. How often is Castle Biosciences' 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 CSTL, twice per month. The most recent reporting period available is March, 15 2025. More Short Interest Resources from MarketBeat Related Companies PGNY Short Interest Data AGL Short Interest Data PACS Short Interest Data ADUS Short Interest Data TDOC Short Interest Data AHCO Short Interest Data VRDN Short Interest Data GRAL Short Interest Data AVAH Short Interest Data CDNA 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:CSTL) was last updated on 3/28/2025 by MarketBeat.com Staff From Our PartnersElon Warns: Exec Order 14024 Targets DollarExecutive Order 14024 is paving the way for irreversible damage to the dollar's value—threatening your wealth,...Priority Gold | SponsoredDo this Before Elon's Reveal on April 23rdElon’s newest tech could pay you an extra $30,000 a year — while you sleep. 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