Castle Biosciences (CSTL) Short Interest Ratio & Short Volume $16.02 -0.48 (-2.91%) Closing price 03:59 PM EasternExtended Trading$16.00 -0.03 (-0.16%) As of 04:04 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 1.51 million shares. This marks a 3.42% increase in short interest from the previous month. The short interest ratio (days to cover) is 3.3, indicating that it would take 3.3 days of the average trading volume of 404,697 shares to cover all short positions.Current Short Interest1,510,000 sharesPrevious Short Interest1,460,000 sharesChange Vs. Previous Month+3.42%Dollar Volume Sold Short$30.28 millionShort Interest Ratio3.3 Days to CoverLast Record DateApril 30, 2025Outstanding Shares28,872,000 sharesPercentage of Shares Shorted5.23%Today's Trading Volume195,998 sharesAverage Trading Volume404,697 sharesToday's Volume Vs. Average48% 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 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 4/30/20251,510,000 shares $30.28 million +3.4%N/A3.3 $20.05 4/15/20251,460,000 shares $30.73 million -12.6%5.6%3.6 $21.05 3/31/20251,670,000 shares $33.43 million -5.1%6.4%3.7 $20.02 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 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. 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 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 $17.30While others chase AI stocks, smart traders do this (Ad)Since the pandemic, the average mortgage payment has jumped from $1,427 to $2,047. That's an extra $600 every single month just vanishing from people's pockets. Meanwhile, credit card debt is hitting record highs, and savings accounts are at their lowest since 2008. Most folks are left with two options… Get a second job... or work overtime on weekends. But what if there was a third option? I just uncovered a shocking anomaly in the options market that could change everything... One that lets you target extra cash on days when most people make nothing - weekends. Think what that could mean for your monthly budget...you can get the full story here 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 $16.85 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 $64.44While others chase AI stocks, smart traders do this (Ad)Since the pandemic, the average mortgage payment has jumped from $1,427 to $2,047. That's an extra $600 every single month just vanishing from people's pockets. Meanwhile, credit card debt is hitting record highs, and savings accounts are at their lowest since 2008. Most folks are left with two options… Get a second job... or work overtime on weekends. But what if there was a third option? I just uncovered a shocking anomaly in the options market that could change everything... One that lets you target extra cash on days when most people make nothing - weekends. Think what that could mean for your monthly budget...you can get the full story here 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 $73.33 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 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 covered or closed out. As of April 30th, traders have sold 1,510,000 shares of CSTL 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 3.0. 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: Torno Capital LLC, and Simplex Trading LLC. These positions are disclosed in Form 13F filings with the Securities and Exchange Commission. Is Castle Biosciences' short interest increasing or decreasing? Castle Biosciences saw a increase in short interest during the month of April. As of April 30th, there was short interest totaling 1,510,000 shares, an increase of 3.4% from the previous total of 1,460,000 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? Here is how the short interest of companies in the industry of "healthcare" compare to Castle Biosciences: Progyny, Inc. (9.57%), PACS Group, Inc. (6.95%), GeneDx Holdings Corp. (14.32%), Teladoc Health, Inc. (11.91%), Grail, Inc. (19.18%), AdaptHealth Corp. (11.55%), agilon health, inc. (7.25%), Aveanna Healthcare Holdings Inc. (3.19%), Viridian Therapeutics, Inc. (12.40%), The Pennant Group, Inc. (1.68%), Which stocks are the most shorted right now? As of the most recent reporting period, the following stocks had the largest short interest positions: Spotify Technology S.A. ($4.67 billion), Charter Communications, Inc. ($4.58 billion), Capital One Financial Co. ($4.47 billion), The Kroger Co. ($2.56 billion), Reddit, Inc. ($2.23 billion), Rivian Automotive, Inc. ($2.16 billion), Live Nation Entertainment, Inc. ($1.90 billion), SoFi Technologies, Inc. ($1.85 billion), Zscaler, Inc. ($1.75 billion), and Omnicom Group Inc. ($1.75 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 $0.48 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 appreciates 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 April, 30 2025. More Short Interest Resources from MarketBeat Related Companies PGNY Short Interest Data PACS Short Interest Data WGS Short Interest Data TDOC Short Interest Data GRAL Short Interest Data AHCO Short Interest Data AGL Short Interest Data AVAH Short Interest Data VRDN Short Interest Data PNTG 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 5/21/2025 by MarketBeat.com Staff From Our PartnersMarket Panic: Trump Just Dropped a Bomb on Your Stockstock Market Panic: Trump Just Dropped a Bomb on Your Stocks The market is in freefall—and Trump's new tarif...American Alternative | SponsoredGold Hits New Highs as Global Markets SpiralWhen Trump took office in 2017, gold was just $1,100 an ounce. By the time he left, it had soared to $1,839. ...Premier Gold Co | SponsoredWhite House to reset Social Security?Elon Musk's parting DOGE gift looks set to shock America... A single announcement by July 22nd could soon b...Altimetry | SponsoredThe Trump Dump is starting; Get out of stocks now?The first 365 days of the Trump presidency… Will be the best time to get rich in American history.Paradigm Press | SponsoredTrump’s treachery Trump’s Final Reset Inside the shocking plot to re-engineer America’s financial system…and why you need to ...Porter & Company | SponsoredBuffett’s favorite chart just hit 209% – here’s what that means for goldA Historic Gold Announcement Is About to Rock Wall Street For months, sharp-eyed analysts have watched the ...Golden Portfolio | SponsoredSilicon Valley Gold RushA new technology has sparked a modern-day gold rush in Silicon Valley. OpenAI’s Sam Altman invested $375M. Bil...Stansberry Research | SponsoredEveryone’s watching Nvidia right now. Here’s why I’m excited.So, unless you’ve been living under a rock, you probably saw the news… Nvidia just signed a $7 BILLION deal...Timothy Sykes | Sponsored Adding Choose a watchlist: Watchlist Adding You have already added five stocks to your watchlist. Upgrade to MarketBeat All Access to add more stocks to your watchlist. Adding Castle Biosciences, Inc. Please log in to your account or sign up in order to add this asset to your watchlist. Share Castle Biosciences With A Colleague Link copied to clipboard. Get 30 Days of MarketBeat All Access for Free Sign up for MarketBeat All Access to gain access to MarketBeat's full suite of research tools. Start Your 30-Day Trial MarketBeat All Access Features Best-in-Class Portfolio Monitoring Get personalized stock ideas. Compare portfolio to indices. Check stock news, ratings, SEC filings, and more. Stock Ideas and Recommendations See daily stock ideas from top analysts. Receive short-term trading ideas from MarketBeat. Identify trending stocks on social media. Advanced Stock Screeners and Research Tools Use our seven stock screeners to find suitable stocks. Stay informed with MarketBeat's real-time news. Export data to Excel for personal analysis. Sign in to your free account to enjoy these benefits In-depth profiles and analysis for 20,000 public companies. Real-time analyst ratings, insider transactions, earnings data, and more. Our daily ratings and market update email newsletter. Sign in to your free account to enjoy all that MarketBeat has to offer. Sign In Create Account Your Email Address: Email Address Required Your Password: Password Required Log In or Sign in with Facebook Sign in with Google Forgot your password? Your Email Address: Please enter your email address. Please enter a valid email address Choose a Password: Please enter your password. Your password must be at least 8 characters long and contain at least 1 number, 1 letter, and 1 special character. Create My Account (Free) or Sign in with Facebook Sign in with Google By creating a free account, you agree to our terms of service. This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Buy CSTL Stock Free CSTL Stock Alerts