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Ionis Pharmaceuticals Inc. short interest

20.7M shares of Ionis Pharmaceuticals were sold short at the 15 October 2026 settlement, near the top of its range over the last year (12.7M to 22.5M). Short sellers would need 7.7 days of normal trading to buy them back.

Shares sold short20.7Mat 15 Oct 2026
Change on the settlement before-8.2%+51% over a year
Days to cover7.65at 2.7M shares a day
Of shares in issue12.47%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 near the top of its range over the last year (12.7M to 22.5M), and the share price moved -39% 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. Counts before a split are restated to today's shares, the way the price is.

How it compares

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    Every settlement since 29 Dec 2017 as a table
    SettlementShares shortChangeAverage daily volumeDays to cover
    15 October 202620.7M-8.2%2.7M7.65
    30 September 202622.5M+7.7%4.9M4.61
    15 September 202620.9M-0.2%4.0M5.20
    31 August 202620.9M+0.1%2.3M9.18
    14 August 202620.9M-2.6%2.2M9.62
    31 July 202621.5M+7.1%3.4M6.35
    15 July 202620.0M+15.0%5.5M3.68
    30 June 202617.4M-1.9%2.4M7.33
    15 June 202617.8M+4.5%1.7M10.64
    29 May 202617.0M+5.6%1.7M9.98
    15 May 202616.1M-1.2%1.6M10.00
    30 April 202616.3M+18.3%2.0M8.04
    15 April 202613.8M-4.0%1.4M9.54
    31 March 202614.3M+2.7%2.4M5.93
    13 March 202613.9M-9.0%2.5M5.68
    27 February 202615.3M-1.1%2.2M6.91
    13 February 202615.5M-0.3%1.9M8.37
    30 January 202615.5M+13.2%2.7M5.82
    15 January 202613.7M-7.8%2.1M6.59
    31 December 202514.9M-7.5%1.6M9.49
    15 December 202516.1M+2.9%2.0M7.96
    28 November 202515.6M+9.9%2.6M5.95
    14 November 202514.2M+12.3%3.7M3.81
    31 October 202512.7M-7.6%1.9M6.61
    15 October 202513.7M+11.6%2.3M6.01
    30 September 202512.3M+2.6%2.0M6.16
    15 September 202512.0M+14.0%4.8M2.49
    29 August 202510.5M-2.6%1.8M5.94
    15 August 202510.8M-6.9%2.2M5.01
    31 July 202511.6M-10.2%1.8M6.51
    15 July 202512.9M-8.8%2.2M5.85
    30 June 202514.1M-0.6%2.0M7.23
    13 June 202514.2M-4.1%1.4M9.94
    30 May 202514.8M-2.8%1.4M10.52
    15 May 202515.3M+4.4%1.6M9.36
    30 April 202514.6M+0.6%1.4M10.37
    15 April 202514.5M+9.1%2.4M6.17
    31 March 202513.3M+4.1%1.4M9.56
    14 March 202512.8M-0.3%1.7M7.50
    28 February 202512.9M+1.4%2.0M6.37
    14 February 202512.7M+4.5%1.3M9.46
    31 January 202512.1M+18.4%1.8M6.62
    15 January 202510.2M-6.1%1.4M7.27
    31 December 202410.9M+3.5%1.7M6.48
    13 December 202410.5M+0.8%1.4M7.63
    29 November 202410.4M-5.4%1.6M6.40
    15 November 202411.1M+2.9%1.2M9.24
    31 October 202410.7M+8.8%1.2M8.88
    15 October 20249.9M-6.3%1.4M6.95
    30 September 202410.5M-0.8%1.8M5.81
    13 September 202410.6M+4.5%3.0M3.53
    30 August 202410.2M+2.6%911K11.15
    15 August 20249.9M+4.7%1.1M8.75
    31 July 20249.5M+1.0%1.3M7.22
    15 July 20249.4M-1.6%1.3M7.23
    28 June 20249.5M+10.0%2.1M4.61
    14 June 20248.7M+0.6%935K9.25
    31 May 20248.6M-0.3%1.4M6.34
    15 May 20248.6M-1.5%1.1M7.82
    30 April 20248.8M-8.2%846K10.34
    15 April 20249.5M+0.1%883K10.79
    28 March 20249.5M-1.5%953K10.00
    15 March 20249.7M+6.1%1.1M8.96
    29 February 20249.1M+0.5%1.6M5.54
    15 February 20249.1M+7.3%1.0M8.84
    31 January 20248.5M-1.1%1.3M6.48
    12 January 20248.5M+3.6%1.2M7.14
    29 December 20238.2M-3.7%1.1M7.55
    15 December 20238.6M-11.8%1.2M6.86
    30 November 20239.7M-0.4%796K12.19
    15 November 20239.7M+0.4%1.2M7.87
    31 October 20239.7M+6.3%1.0M9.48
    13 October 20239.1M-1.9%1.2M7.78
    29 September 20239.3M-0.8%1.3M7.26
    15 September 20239.4M+0.9%951K9.86
    31 August 20239.3M-3.7%626K14.84
    15 August 20239.6M+4.7%769K12.55
    31 July 20239.2M+3.9%1.3M6.88
    14 July 20238.9M+2.8%847K10.46
    30 June 20238.6M-0.8%1.2M7.26
    15 June 20238.7M+33.3%2.0M4.27
    31 May 20236.5M-8.3%1.4M4.63
    15 May 20237.1M+1.3%863K8.24
    28 April 20237.0M+1.5%897K7.83
    14 April 20236.9M-6.4%872K7.93
    31 March 20237.4M-3.6%1.1M6.95
    15 March 20237.7M-6.2%753K10.17
    28 February 20238.2M+8.8%1.0M7.99
    15 February 20237.5M-8.2%669K11.22
    31 January 20238.2M+0.5%929K8.80
    13 January 20238.1M-6.3%1.4M5.86
    30 December 20228.7M+19.2%1.1M7.77
    15 December 20227.3M-8.7%1.1M6.77
    30 November 20228.0M+3.5%943K8.46
    15 November 20227.7M+12.6%1.1M7.34
    31 October 20226.9M-2.1%1.0M6.60
    14 October 20227.0M-3.5%887K7.89
    30 September 20227.3M+6.7%1.3M5.77
    15 September 20226.8M+9.1%1.1M6.01
    31 August 20226.2M-7.8%672K9.27
    15 August 20226.8M+10.7%1.2M5.73
    29 July 20226.1M+0.6%652K9.36
    15 July 20226.1M+6.0%965K6.29
    30 June 20225.7M+1.3%974K5.88
    15 June 20225.7M-5.6%872K6.48
    31 May 20226.0M-16.1%1.2M5.06
    13 May 20227.1M+9.1%1.2M6.05
    29 April 20226.5M-12.1%1.2M5.43
    14 April 20227.4M+3.9%1.2M6.12
    31 March 20227.2M-1.7%942K7.61
    15 March 20227.3M-4.1%858K8.50
    28 February 20227.6M-18.7%1.1M6.82
    15 February 20229.4M-1.8%1.2M7.94
    31 January 20229.5M+31.8%1.7M5.64
    14 January 20227.2M-1.4%1.0M6.92
    31 December 20217.3M-0.8%968K7.57
    15 December 20217.4M+8.2%1.7M4.44
    30 November 20216.8M+10.3%1.2M5.61
    15 November 20216.2M-10.4%752K8.23
    29 October 20216.9M+1.9%1.4M4.92
    15 October 20216.8M+2.1%735K9.23
    30 September 20216.6M-7.4%1.0M6.45
    15 September 20217.2M-6.7%925K7.75
    31 August 20217.7M-8.5%714K10.77
    13 August 20218.4M-8.6%683K12.31
    30 July 20219.2M+7.3%1.1M8.67
    15 July 20218.6M-4.8%1.0M8.41
    30 June 20219.0M+0.4%1.5M5.96
    15 June 20219.0M-17.3%1.7M5.24
    28 May 202110.8M+1.0%2.3M4.76
    14 May 202110.7M+4.2%2.2M4.95
    30 April 202110.3M+6.7%1.2M8.67
    15 April 20219.7M+10.2%1.6M5.97
    31 March 20218.8M+2.1%2.0M4.40
    15 March 20218.6M+1.0%796K10.79
    26 February 20218.5M+7.1%762K11.15
    12 February 20217.9M+5.1%762K10.42
    29 January 20217.6M+2.6%781K9.67
    15 January 20217.4M-5.3%851K8.65
    31 December 20207.8M+7.6%1.5M5.08
    15 December 20207.2M+2.2%979K7.38
    30 November 20207.1M+4.1%626K11.30
    13 November 20206.8M-24.6%938K7.24
    30 October 20209.0M-11.7%960K9.38
    15 October 202010.2M+0.1%1.4M7.04
    30 September 202010.2M+3.0%1.4M7.29
    15 September 20209.9M+4.0%858K11.52
    31 August 20209.5M-0.7%609K15.61
    14 August 20209.6M-6.0%913K10.48
    31 July 202010.2M-4.6%605K16.82
    15 July 202010.7M-1.1%771K13.84
    30 June 202010.8M-5.8%1.0M10.52
    15 June 202011.5M+4.0%948K12.08
    29 May 202011.0M+4.6%916K12.01
    15 May 202010.5M+4.5%974K10.81
    30 April 202010.1M-4.6%907K11.11
    15 April 202010.6M+0.5%975K10.83
    31 March 202010.5M-4.6%1.4M7.36
    13 March 202011.0M+0.1%1.5M7.35
    28 February 202011.0M+0.4%1.2M8.88
    14 February 202011.0M-9.7%874K12.54
    31 January 202012.1M+12.1%1.2M10.15
    15 January 202010.8M+2.0%839K12.90
    31 December 201910.6M+10.2%1.0M10.56
    13 December 20199.6M-9.6%1.3M7.13
    29 November 201910.6M-1.7%1.2M8.76
    15 November 201910.8M-4.8%1.1M9.87
    31 October 201911.4M-9.3%1.6M7.03
    15 October 201912.5M-4.5%900K13.93
    30 September 201913.1M-6.7%1.3M10.47
    13 September 201914.1M+0.3%1.4M9.73
    30 August 201914.0M-12.7%1.2M12.10
    15 August 201916.1M-2.9%1.5M10.96
    31 July 201916.6M-9.9%1.5M11.05
    15 July 201918.4M-5.0%1.2M15.47
    28 June 201919.3M+2.3%1.3M15.32
    14 June 201918.9M-1.1%1.4M13.71
    31 May 201919.1M+18.4%2.4M7.91
    15 May 201916.1M+26.6%2.3M7.06
    30 April 201912.7M-0.2%1.9M6.87
    15 April 201912.8M-3.4%1.4M9.23
    29 March 201913.2M-9.3%1.4M9.60
    15 March 201914.6M-6.4%1.5M9.65
    28 February 201915.6M-3.1%1.7M9.08
    15 February 201916.1M+4.4%801K20.08
    31 January 201915.4M-4.9%1.1M14.62
    15 January 201916.2M+5.5%1.3M12.80
    31 December 201815.4M-4.7%1.1M13.36
    14 December 201816.1M+2.5%1.3M12.89
    30 November 201815.7M-2.4%966K16.28
    15 November 201816.1M-0.3%1.5M10.64
    31 October 201816.2M-2.4%1.3M12.76
    15 October 201816.6M+5.8%1.7M9.74
    28 September 201815.7M-8.6%1.5M10.44
    14 September 201817.1M+0.7%1.2M14.71
    31 August 201817.0M-3.5%2.0M8.30
    15 August 201817.6M+5.5%1.4M12.59
    31 July 201816.7M+4.5%951K17.58
    13 July 201816.0M+0.3%813K19.66
    29 June 201815.9M+4.7%1.6M9.74
    15 June 201815.2M+3.6%985K15.46
    31 May 201814.7M-3.3%1.1M13.55
    15 May 201815.2M+15.8%2.1M7.16
    30 April 201813.1M-3.6%2.2M5.98
    13 April 201813.6M+1.6%1.3M10.31
    29 March 201813.4M+5.8%1.4M9.28
    15 March 201812.7M-2.9%1.5M8.18
    28 February 201813.0M+2.2%1.0M12.57
    15 February 201812.8M-14.3%1.2M10.43
    31 January 201814.9M+8.5%1.3M11.64
    12 January 201813.7M-6.0%1.3M10.29
    29 December 201714.6M774K18.86
    Shares in millions (M) or thousands (K); hold the pointer on a figure for the exact count. Counts before a split are restated to today's shares. FINRA publishes consolidated short interest twice a month, about ten days after each settlement.