Atara Biotherapeutics (ATRA) Short Interest Ratio & Short Volume $11.94 -0.18 (-1.49%) Closing price 09/15/2025 04:00 PM EasternExtended Trading$11.78 -0.16 (-1.34%) As of 08:04 AM 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 Atara Biotherapeutics Short Interest DataAtara Biotherapeutics (ATRA) has a short interest of 173,800 shares, representing 4.46% of the float (the number of shares available for trading by the public). This marks a -11.42% decrease 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 49,604 shares to cover all short positions.Current Short Interest173,800 sharesPrevious Short Interest196,200 sharesChange Vs. Previous Month-11.42%Dollar Volume Sold Short$2.09 millionShort Interest Ratio3.3 Days to CoverLast Record DateAugust 31, 2025Outstanding Shares7,020,000 sharesFloat Size3,900,000 sharesShort Percent of Float4.46%Today's Trading Volume31,487 sharesAverage Trading Volume49,604 sharesToday's Volume Vs. Average63% Short Selling Atara Biotherapeutics? Sign up to receive the latest short interest report for Atara Biotherapeutics and its competitors with MarketBeat's FREE newsletter. 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Skip Charts & View Short Interest HistoryShort Interest ChartDays to Cover ChartShort Percent of Float ChartATRA Short Interest Over TimeATRA Days to Cover Over TimeATRA Percentage of Float Shorted Over Time Atara Biotherapeutics Short Interest History Export to ExcelReport DateTotal Shares Sold ShortDollar Volume Sold ShortChange from Previous ReportPercentage of Float ShortedDays to CoverPrice on Report Date 8/31/2025173,800 shares $2.09 million -11.4%4.5%3.3 $12.05 8/15/2025196,200 shares $2.41 million -6.8%5.0%3.5 $12.29 7/31/2025210,600 shares $2.43 million -21.4%5.5%3.6 $11.52 7/15/2025268,000 shares $2.48 million +0.5%7.0%4.4 $9.27 6/30/2025266,700 shares $2.06 million -6.7%8.1%4.9 $7.72 6/15/2025285,800 shares $2.52 million -22.2%8.6%5 $8.82 5/31/2025367,400 shares $2.86 million -11.0%10.9%6.1 $7.78 5/15/2025412,900 shares $3.14 million -20.9%12.3%6.9 $7.61 4/30/2025522,100 shares $4.17 million -21.2%13.7%8.5 $7.99 4/15/2025662,200 shares $3.96 million -0.7%17.6%6.7 $5.98 Get the Latest News and Ratings for ATRA and Related StocksEnter your email address below to receive the latest news and analysts' ratings for Atara Biotherapeutics and its competitors with MarketBeat's FREE daily newsletter. 3/31/2025666,800 shares $3.96 million -7.8%17.6%3.6 $5.94 3/15/2025723,300 shares $5.24 million +1.2%19.0%3.7 $7.25 2/28/2025715,100 shares $4.94 million +6.0%18.8%3.5 $6.91 2/15/2025674,600 shares $5.79 million -4.5%18.1%3.3 $8.59 1/31/2025706,500 shares $6.27 million +29.0%18.9%3.3 $8.88 1/15/2025547,800 shares $7.21 million +2.7%12.7%2.7 $13.16 12/31/2024533,600 shares $7.10 million -3.3%12.4%4.8 $13.31 12/15/2024551,500 shares $5.70 million +1.4%13.0%5.4 $10.33 11/30/2024544,000 shares $6.62 million +4.7%13.0%5.1 $12.18 11/15/2024519,500 shares $6.23 million -18.4%12.4%3.5 $12.00 10/31/2024636,300 shares $5.67 million -0.5%16.0%4.6 $8.91 10/15/2024639,200 shares $5.36 million +21.4%16.1%5.4 $8.38 9/30/2024526,400 shares $4.28 million +13.7%13.3%4.5 $8.13 9/15/2024463,000 shares $4.50 million +12.8%12.6%3.6 $9.72 8/31/2024410,500 shares $3.12 million +8.5%11.0%3.2 $7.60 8/15/2024378,500 shares $2.59 million +5.0%9.4%4.7 $6.83 7/31/2024360,500 shares $3.54 million -33.2%9.0%4.5 $9.83 7/15/2024540,000 shares $6.03 million -6.1%13.4%6.7 $11.16 6/30/2024575,300 shares $4.89 million +33.5%14.4%7.6 $8.50 6/15/2024431,000 shares $5.51 million -96.2%10.8%7.2 $12.78 5/31/202411,270,000 shares $6.32 million -3.0%N/A8.5 $0.56 5/15/202411,620,000 shares $7.44 million -2.2%N/A7.2 $0.64 4/30/202411,880,000 shares $8.20 million +3.8%N/A6.9 $0.69 4/15/202411,450,000 shares $7.77 million +2.0%N/A4.4 $0.68 3/31/202411,230,000 shares $7.79 million +1.8%N/A3.7 $0.69 3/15/202411,030,000 shares $6.85 million +8.8%N/A3.2 $0.62 2/29/202410,140,000 shares $7.89 million -6.7%N/A2.8 $0.78 2/15/202410,870,000 shares $8.39 million +44.4%N/A2.9 $0.77 1/31/20247,530,000 shares $4.70 million +2.7%N/A1.3 $0.62 1/15/20247,330,000 shares $5.27 million -20.2%N/A1.4 $0.72 12/31/20239,190,000 shares $4.71 million -9.3%N/A1.9 $0.51 12/15/202310,130,000 shares $6.08 million -8.8%N/A2.2 $0.60 11/30/202311,110,000 shares $7.33 million +36.2%N/A2.8 $0.66 11/15/20238,160,000 shares $3.10 million -34.7%N/A2.2 $0.38 10/31/202312,490,000 shares $16.11 million +1.8%N/A6.1 $1.29 10/15/202312,270,000 shares $18.90 million +6.3%N/A10.5 $1.54 9/30/202311,540,000 shares $17.08 million -1.1%N/A9.5 $1.48 9/15/202311,670,000 shares $17.86 million +1.2%N/A9.7 $1.53 8/31/202311,530,000 shares $16.83 million -5.4%N/A7.5 $1.46 8/15/202312,190,000 shares $22.43 million -5.9%N/A6.9 $1.84 7/31/202312,950,000 shares $28.62 million +2.6%N/A6.9 $2.21 7/15/202312,620,000 shares $23.09 million +7.9%N/A6.7 $1.83 6/30/202311,700,000 shares $18.84 million -11.4%N/A6 $1.61 6/15/202313,200,000 shares $28.25 million +4.6%N/A7 $2.14 5/31/202312,620,000 shares $19.31 million -11.0%N/A7.6 $1.53 5/15/202314,180,000 shares $31.20 million -20.3%N/A10 $2.20 4/30/202317,790,000 shares $48.21 million -7.4%N/A13.8 $2.71 4/15/202319,210,000 shares $51.67 million -3.8%N/A15.9 $2.69 3/31/202319,960,000 shares $57.88 million +19.5%N/A17.1 $2.90 3/15/202316,700,000 shares $51.44 million +18.7%N/A13.1 $3.08 2/28/202314,070,000 shares $56.98 million +0.4%N/A11.3 $4.05 2/15/202314,010,000 shares $63.47 million -1.3%N/A11.4 $4.53 1/31/202314,190,000 shares $71.94 million +4.1%N/A10.3 $5.07 1/15/202313,630,000 shares $53.02 million +4.8%N/A9.5 $3.89 12/30/202213,010,000 shares $42.67 million +5.0%N/A9.1 $3.28 12/15/202212,390,000 shares $42.87 million +1.2%N/A8.4 $3.46 11/30/202212,240,000 shares $55.45 million +1.6%N/A8.4 $4.53 11/15/202212,050,000 shares $60.37 million +1.1%N/A7.7 $5.01 10/31/202211,920,000 shares $55.55 million +0.2%N/A6.9 $4.66 10/15/202211,900,000 shares $44.39 million -3.4%N/A5.7 $3.73 9/30/202212,320,000 shares $46.57 million -0.2%N/A4.6 $3.78 9/15/202212,350,000 shares $58.05 million +10.2%N/A4.7 $4.70 8/31/202211,210,000 shares $44.95 million -0.6%N/A4.4 $4.01 8/15/202211,280,000 shares $60.24 million +7.0%N/A4.7 $5.34 7/31/202210,540,000 shares $31.94 million +31.1%N/A4.8 $3.03 7/15/20228,040,000 shares $30.95 million -24.9%N/A4.4 $3.85 6/30/202210,700,000 shares $83.35 million -5.1%N/A9.2 $7.79 6/15/202211,270,000 shares $62.55 million -3.9%N/A10.2 $5.55 5/31/202211,730,000 shares $61.00 million +6.4%N/A11 $5.20 5/15/202211,020,000 shares $0.00 -6.5%N/A9.9 $0.00 4/30/202211,790,000 shares $74.98 million +6.0%N/A11.7 $6.36 4/15/202211,120,000 shares $89.07 million +14.3%N/A11.2 $8.01 3/31/20229,730,000 shares $90.39 million +11.3%N/A9.6 $9.29 3/15/20228,740,000 shares $74.38 million +20.6%N/A9 $8.51 2/28/20227,250,000 shares $93.16 million +2.6%N/A7.7 $12.85 2/15/20227,070,000 shares $105.84 million +1.4%N/A8.6 $14.97 1/31/20226,970,000 shares $107.06 million +17.3%N/A8.1 $15.36 1/15/20225,940,000 shares $95.46 million -36.9%N/A7.1 $16.07 12/31/20219,420,000 shares $148.46 million +3.4%N/A11.3 $15.76 12/15/20219,110,000 shares $146.03 million +4.8%N/A10.7 $16.03 11/30/20218,690,000 shares $155.46 million -3.3%N/A11 $17.89 11/15/20218,990,000 shares $153.46 million -17.0%N/A10.7 $17.07 10/29/202110,830,000 shares $167.65 million -1.3%N/A13.4 $15.48 10/15/202110,970,000 shares $165.87 million -6.4%13.4%14.3 $15.12 9/30/202111,720,000 shares $209.79 million -6.1%14.4%16.4 $17.90 9/15/202112,480,000 shares $198.43 million +2.1%15.3%16.8 $15.90 8/31/202112,220,000 shares $183.06 million -4.4%15.0%16.2 $14.98 8/13/202112,780,000 shares $159.11 million -2.1%15.7%17.2 $12.45 7/30/202113,060,000 shares $166.52 million +8.0%16.1%16.7 $12.75 7/15/202112,090,000 shares $165.39 million +3.7%14.9%14.4 $13.68 6/30/202111,660,000 shares $181.31 million -7.7%14.4%12.4 $15.55 6/15/202112,630,000 shares $176.82 million -0.5%15.6%14.3 $14.00 5/28/202112,690,000 shares $172.08 million -0.7%15.7%13.9 $13.56 5/14/202112,780,000 shares $188.12 million +5.3%N/A13.5 $14.72 4/30/202112,140,000 shares $176.39 million -2.9%N/A13.2 $14.53 4/15/202112,500,000 shares $173.13 million -4.7%N/A0 $13.85 3/31/202113,120,000 shares $186.57 million +12.0%N/A15.2 $14.22 3/15/202111,710,000 shares $197.90 million +5.5%N/A13 $16.90 2/26/202111,100,000 shares $184.37 million -5.5%N/A11.6 $16.61 2/12/202111,740,000 shares $225.64 million -0.7%N/A12.4 $19.22 1/29/202111,820,000 shares $224.58 million +5.0%N/A11.7 $19.00 1/15/202111,260,000 shares $212.25 million -6.1%N/A11.6 $18.85 12/31/202011,990,000 shares $246.03 million -3.8%N/A13.3 $20.52 12/15/202012,460,000 shares $292.56 million +1.0%N/A14.2 $23.48 11/30/202012,340,000 shares $287.15 million -10.1%N/A13.5 $23.27 11/15/202013,730,000 shares $247.83 million -10.3%N/A16.4 $18.05 10/30/202015,310,000 shares $206.69 million -0.8%N/A19.7 $13.50 10/15/202015,440,000 shares $214.15 million +9.0%N/A19.1 $13.87 9/30/202014,170,000 shares $183.64 million +3.3%N/A17.4 $12.96 ATRA Short Interest - Frequently Asked Questions What is Atara Biotherapeutics' current short interest? Short interest is the volume of Atara Biotherapeutics shares that have been sold short but have not yet been covered or closed out. As of August 31st, investors have sold 173,800 shares of ATRA short. 4.46% of Atara Biotherapeutics' shares are currently sold short. Learn More on Atara Biotherapeutics' current short interest. What is a good short interest ratio for Atara Biotherapeutics? 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. ATRA shares currently have a short interest ratio of 3.0. Learn More on Atara Biotherapeutics's short interest ratio. What is a good short interest percentage for Atara Biotherapeutics? 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. 4.46% of Atara Biotherapeutics' floating shares are currently sold short. Is Atara Biotherapeutics' short interest increasing or decreasing? Atara Biotherapeutics saw a drop in short interest in the month of August. As of August 31st, there was short interest totaling 173,800 shares, a drop of 11.4% from the previous total of 196,200 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 Atara Biotherapeutics' float size? Atara Biotherapeutics currently has issued a total of 7,020,000 shares. Some of Atara Biotherapeutics' 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. Atara Biotherapeutics currently has a public float of 3,900,000 shares. How does Atara Biotherapeutics' short interest compare to its competitors? 4.46% of Atara Biotherapeutics' shares are currently sold short. Here is how the short interest of companies in the industry of "pharmaceutical products" compare to Atara Biotherapeutics: Oric Pharmaceuticals, Inc. (9.03%), I-Mab Sponsored ADR (3.12%), Upexi, Inc. (10.49%), Rocket Pharmaceuticals, Inc. (19.08%), Abeona Therapeutics Inc. (19.80%), Canopy Growth Corporation (6.82%), 4D Molecular Therapeutics, Inc. (10.18%), Altimmune, Inc. (31.73%), Aldeyra Therapeutics, Inc. (9.77%), Foghorn Therapeutics Inc. (3.07%), Which stocks are the most shorted right now? As of the most recent reporting period, the following stocks had the largest short interest positions: SPDR S&P 500 ETF Trust ($73.23 billion), Invesco QQQ ($29.52 billion), iShares Russell 2000 ETF ($20.82 billion), iShares 20+ Year Treasury Bond ETF ($10.76 billion), Palo Alto Networks, Inc. ($9.37 billion), Strategy Inc ($7.58 billion), Invesco S&P 500 Equal Weight ETF ($6.78 billion), SPDR S&P Biotech ETF ($6.72 billion), AppLovin Corporation ($6.37 billion), and iShares iBoxx $ Investment Grade Corporate Bond ETF ($6.29 billion). View all of the most shorted stocks. What does it mean to sell short Atara Biotherapeutics stock? Short selling ATRA is an investing strategy that aims to generate trading profit from Atara Biotherapeutics as its price is falling. ATRA shares are trading down $0.18 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 Atara Biotherapeutics? A short squeeze for Atara Biotherapeutics 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 ATRA, which in turn drives the price of the stock up even further. How often is Atara Biotherapeutics' 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 ATRA, twice per month. The most recent reporting period available is August, 31 2025. More Short Interest Resources from MarketBeat Related Companies ORIC Short Interest Data IMAB Short Interest Data UPXI Short Interest Data RCKT Short Interest Data ABEO Short Interest Data CGC Short Interest Data FDMT Short Interest Data ALT Short Interest Data ALDX Short Interest Data FHTX 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:ATRA) was last updated on 9/16/2025 by MarketBeat.com Staff From Our PartnersNew Biotech Backed by Proven Incubator Now Open to PublicA successful biotech incubator just opened its next chapter - and you're invited to their raise. 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