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Castle Biosciences Inc. short interest

2.0M shares of Castle Biosciences were sold short at the 15 October 2026 settlement, the most since 30 Apr 2021. Short sellers would need 6.0 days of normal trading to buy them back.

Shares sold short2.0Mat 15 Oct 2026
Change on the settlement before+0.8%+25% over a year
Days to cover5.98at 337K shares a day
Of shares in issue6.61%shares short over shares outstanding
New to this? How to read this page
  1. Short interest is the number of shares investors have borrowed and sold, betting the price will fall, and not yet bought back.
  2. Days to cover is shares short over an average day's trading: how many days it would take short sellers to buy them all back. Above 5 or so is high.
  3. Rising short interest says more investors are betting against the stock. A crowded short can also rise fast if shorts rush to buy back.
  4. Brokers report it twice a month to FINRA, about ten days after each settlement date.
  5. What is short interest?

Short interest, days to cover and the price

Short interest is the most since 30 Apr 2021, and the share price moved +71% over the last year.

Shares sold shortDays to coverShare price

Three charts on one timeline. Top: shares sold short at each settlement. Middle: days to cover, taller meaning shorts would need longer to buy back. Bottom: the share price, so you can see whether shorts added as the price fell or rose.

How it compares

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    Every settlement since 31 Jul 2019 as a table
    SettlementShares shortChangeAverage daily volumeDays to cover
    15 October 20262.0M+0.8%337K5.98
    30 September 20262.0M+5.3%420K4.77
    15 September 20261.9M-3.9%258K7.36
    31 August 20262.0M+12.7%391K5.05
    14 August 20261.8M+12.3%477K3.68
    31 July 20261.6M+9.9%492K3.17
    15 July 20261.4M-4.7%251K5.66
    30 June 20261.5M+0.5%469K3.18
    15 June 20261.5M+0.0%284K5.23
    29 May 20261.5M+4.9%393K3.78
    15 May 20261.4M-0.9%634K2.23
    30 April 20261.4M-2.3%302K4.73
    15 April 20261.5M-4.7%278K5.26
    31 March 20261.5M+7.4%315K4.87
    13 March 20261.4M+2.5%408K3.50
    27 February 20261.4M+2.6%483K2.89
    13 February 20261.4M-10.3%439K3.09
    30 January 20261.5M-1.2%372K4.07
    15 January 20261.5M+1.7%381K4.03
    31 December 20251.5M-12.5%286K5.28
    15 December 20251.7M-6.2%435K3.96
    28 November 20251.8M+11.8%492K3.73
    14 November 20251.6M+6.1%673K2.44
    31 October 20251.5M-3.8%241K6.42
    15 October 20251.6M+3.4%295K5.46
    30 September 20251.6M-13.4%330K4.71
    15 September 20251.8M+18.3%416K4.31
    29 August 20251.5M+17.8%467K3.25
    15 August 20251.3M-7.8%959K1.34
    31 July 20251.4M-1.0%385K3.63
    15 July 20251.4M-11.6%331K4.26
    30 June 20251.6M+27.8%492K3.25
    13 June 20251.3M-0.4%432K2.90
    30 May 20251.3M+0.8%368K3.41
    15 May 20251.2M-17.7%656K1.90
    30 April 20251.5M+3.4%441K3.43
    15 April 20251.5M-12.5%343K4.27
    31 March 20251.7M-4.8%317K5.27
    14 March 20251.8M-5.1%564K3.11
    28 February 20251.8M-4.2%443K4.17
    14 February 20251.9M+13.1%390K4.95
    31 January 20251.7M+2.1%368K4.63
    15 January 20251.7M+1.2%626K2.67
    31 December 20241.7M-1.7%229K7.23
    13 December 20241.7M-8.6%365K4.60
    29 November 20241.8M+7.7%289K6.36
    15 November 20241.7M+6.3%554K3.08
    31 October 20241.6M-8.1%335K4.79
    15 October 20241.7M+8.4%413K4.24
    30 September 20241.6M-6.5%374K4.32
    13 September 20241.7M-2.7%278K6.19
    30 August 20241.8M+4.1%381K4.65
    15 August 20241.7M+21.3%631K2.70
    31 July 20241.4M-22.5%369K3.80
    15 July 20241.8M+54.4%435K4.16
    28 June 20241.2M+3.0%305K3.85
    14 June 20241.1M-0.7%259K4.39
    31 May 20241.1M-11.4%232K4.93
    15 May 20241.3M-10.2%342K3.79
    30 April 20241.4M-1.2%159K9.07
    15 April 20241.5M+1.7%142K10.27
    28 March 20241.4M+1.0%227K6.31
    15 March 20241.4M+17.4%327K4.34
    29 February 20241.2M-3.7%316K3.83
    15 February 20241.3M+0.9%208K6.03
    31 January 20241.2M+29.6%233K5.34
    12 January 2024959K+19.8%232K4.14
    29 December 2023800K-18.1%190K4.21
    15 December 2023977K-16.9%283K3.45
    30 November 20231.2M-9.9%185K6.34
    15 November 20231.3M-8.6%336K3.88
    31 October 20231.4M+28.1%315K4.54
    13 October 20231.1M+12.1%265K4.20
    29 September 2023995K+19.4%177K5.61
    15 September 2023833K+16.2%186K4.49
    31 August 2023717K-3.6%217K3.30
    15 August 2023743K-14.1%333K2.23
    31 July 2023865K+1.3%463K1.87
    14 July 2023854K+32.2%2.2M1.00
    30 June 2023646K-26.8%522K1.24
    15 June 2023883K+16.4%1.7M1.00
    31 May 2023759K-13.6%160K4.74
    15 May 2023878K-11.0%136K6.45
    28 April 2023986K+0.7%86K11.44
    14 April 2023979K-5.2%126K7.80
    31 March 20231.0M-2.3%126K8.22
    15 March 20231.1M+22.7%237K4.45
    28 February 2023862K-24.8%146K5.91
    15 February 20231.1M+4.2%125K9.13
    31 January 20231.1M-2.5%107K10.26
    13 January 20231.1M-5.4%156K7.21
    30 December 20221.2M+5.9%177K6.72
    15 December 20221.1M+5.3%161K6.99
    30 November 20221.1M+0.6%189K5.67
    15 November 20221.1M-9.2%260K4.09
    31 October 20221.2M-9.7%229K5.11
    14 October 20221.3M+3.7%207K6.27
    30 September 20221.3M+7.8%170K7.36
    15 September 20221.2M-1.8%155K7.47
    31 August 20221.2M-1.5%154K7.67
    15 August 20221.2M-17.1%289K4.16
    29 July 20221.4M+10.7%167K8.67
    15 July 20221.3M-1.6%314K4.17
    30 June 20221.3M+1.4%465K2.86
    15 June 20221.3M+3.3%319K4.11
    31 May 20221.3M-1.7%315K4.03
    13 May 20221.3M-2.3%404K3.20
    29 April 20221.3M+7.9%699K1.89
    14 April 20221.2M-9.3%359K3.41
    31 March 20221.4M-6.6%138K9.79
    15 March 20221.4M-5.1%175K8.26
    28 February 20221.5M+4.4%214K7.12
    15 February 20221.5M+3.2%217K6.74
    31 January 20221.4M+19.9%334K4.24
    14 January 20221.2M+22.6%227K5.19
    31 December 2021963K-12.8%189K5.09
    15 December 20211.1M+6.5%302K3.65
    30 November 20211.0M+24.0%282K3.67
    15 November 2021835K-1.3%222K3.76
    29 October 2021846K-14.8%151K5.61
    15 October 2021993K-16.7%146K6.78
    30 September 20211.2M-4.1%188K6.33
    15 September 20211.2M-12.1%144K8.63
    31 August 20211.4M+0.0%159K8.92
    13 August 20211.4M+1.7%152K9.33
    30 July 20211.4M-6.5%153K9.11
    15 July 20211.5M-3.3%152K9.77
    30 June 20211.5M+14.4%351K4.38
    15 June 20211.3M-1.0%237K5.67
    28 May 20211.4M+8.6%232K5.84
    14 May 20211.2M-44.2%277K4.50
    30 April 20212.2M+1.9%185K12.12
    15 April 20212.2M-7.1%225K9.75
    31 March 20212.4M+0.7%330K7.18
    15 March 20212.4M+54.7%408K5.76
    26 February 20211.5M+7.0%213K7.14
    12 February 20211.4M-4.4%292K4.86
    29 January 20211.5M-2.6%230K6.47
    15 January 20211.5M-8.8%214K7.13
    31 December 20201.7M+43.7%587K2.85
    15 December 20201.2M-2.4%312K3.72
    30 November 20201.2M-3.9%131K9.09
    13 November 20201.2M-1.8%179K6.92
    30 October 20201.3M+22.4%97K12.97
    15 October 20201.0M+40.7%175K5.88
    30 September 2020734K+40.3%198K3.71
    15 September 2020523K-23.5%216K2.42
    31 August 2020683K-18.1%147K4.65
    14 August 2020834K-5.1%134K6.23
    31 July 2020879K-6.5%98K8.95
    15 July 2020940K-15.2%167K5.62
    30 June 20201.1M-12.9%442K2.51
    15 June 20201.3M-1.2%119K10.64
    29 May 20201.3M+13.2%141K9.10
    15 May 20201.1M+16.6%251K4.52
    30 April 2020975K+12.2%120K8.10
    15 April 2020869K+1.9%97K8.97
    31 March 2020852K+35.8%226K3.77
    13 March 2020628K+38.9%180K3.49
    28 February 2020452K-0.8%123K3.68
    14 February 2020455K-0.4%129K3.54
    31 January 2020457K-14.3%91K5.01
    15 January 2020534K+50.3%94K5.69
    31 December 2019355K+34.5%125K2.83
    13 December 2019264K+10.1%83K3.20
    29 November 2019240K+6.4%83K2.88
    15 November 2019226K-17.5%142K1.59
    31 October 2019273K-5.6%142K1.92
    15 October 2019290K+38.3%87K3.35
    30 September 2019209K+120.2%197K1.06
    13 September 201995K+620.5%104K1.00
    30 August 201913K+246.0%154K1.00
    15 August 20194K-72.1%88K1.00
    31 July 201914K288K1.00
    Shares in millions (M) or thousands (K); hold the pointer on a figure for the exact count. FINRA publishes consolidated short interest twice a month, about ten days after each settlement.