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Ionis Pharmaceuticals (IONS) Short Interest Ratio & Short Volume

Ionis Pharmaceuticals logo
$45.28 +1.98 (+4.57%)
Closing price 04:00 PM Eastern
Extended Trading
$45.08 -0.20 (-0.44%)
As of 07:55 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 Massive. Learn more.
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Ionis Pharmaceuticals Short Interest Overview

As of September 30, 2026, Ionis Pharmaceuticals (IONS) had a short interest of 22.51 million shares sold short, representing 13.79% of the public float. This marks a 7.75% increase in short interest since the prior report. The short interest ratio (days to cover) is 4.6, meaning it would take 4.6 days of the average trading volume of 4.26 million shares to cover all short positions.

Current Short Interest
22,508,744 shares
Previous Short Interest
20,890,252 shares
Change Vs. Previous Month
7.75%
Dollar Volume Sold Short
$1.01 billion
Short Interest Ratio
4.6 Days to Cover
Last Record Date
September 30, 2026
Outstanding Shares
166,180,000 shares
Short Percent of Float
13.79%
Today's Trading Volume
4,862,015 shares
Average Trading Volume
4,263,666 shares
Today's Volume Vs. Average
114%
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Short Interest ChartDays to Cover ChartShort Percent of Float Chart

IONS Short Interest Over Time

IONS Days to Cover Over Time

IONS Percentage of Float Shorted Over Time

Ionis Pharmaceuticals Tesla Short Interest History & Recent Changes

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Report DateTotal Shares Sold ShortDollar Volume Sold ShortChange from Previous ReportPercentage of Float ShortedDays to CoverPrice on Report Date
9/30/202622,508,744 shares $1.01 billion +7.8%13.8%4.61 $44.65
9/15/202620,890,252 shares $987.06 million -0.2%12.8%5.2 $47.25
8/31/202620,924,638 shares $1.26 billion +0.1%12.8%9.18 $60.36
8/14/202620,909,181 shares $1.20 billion -2.6%12.8%9.62 $57.24
7/31/202621,466,123 shares $1.11 billion +7.1%13.2%6.35 $51.77
7/15/202620,042,879 shares $1.10 billion +15.0%12.4%3.68 $54.73
6/30/202617,425,020 shares $1.38 billion -1.9%10.7%7.33 $79.37
6/15/202617,757,362 shares $1.31 billion +4.5%10.9%10.64 $73.96
5/29/202616,986,466 shares $1.30 billion +5.6%10.5%9.98 $76.50
5/15/202616,086,234 shares $1.19 billion -1.2%10.0%10 $74.23
4/30/202616,279,706 shares $1.22 billion +18.3%10.1%8.04 $74.76
4/15/202613,762,159 shares $1.06 billion -4.0%8.5%9.54 $76.82
3/31/202614,330,826 shares $1.08 billion +2.7%8.8%5.93 $75.09
3/13/202613,949,702 shares $993.08 million -9.0%8.7%5.68 $71.19
2/27/202615,323,236 shares $1.24 billion -1.1%9.5%6.91 $81.15
2/13/202615,487,922 shares $1.25 billion -0.3%9.5%8.37 $80.60
1/30/202615,537,729 shares $1.28 billion +13.2%9.9%5.82 $82.67
1/15/202613,729,783 shares $1.06 billion -7.8%8.7%6.59 $77.21
12/31/202514,885,370 shares $1.18 billion -7.5%9.4%9.49 $79.11
12/15/202516,086,183 shares $1.28 billion +2.9%10.2%7.96 $79.76
11/28/202515,626,208 shares $1.29 billion +9.9%9.9%5.95 $82.75
11/14/202514,223,973 shares $1.02 billion +12.3%9.2%3.81 $71.55
10/31/202512,661,274 shares $940.73 million -7.6%8.2%6.61 $74.30
10/15/202513,700,000 shares $991.74 million +11.6%8.7%5.5 $72.39
9/30/202512,280,000 shares $803.36 million +2.6%7.8%5 $65.42
9/15/202511,970,000 shares $731.37 million +14.0%7.6%4.9 $61.10
8/31/202510,500,000 shares $447.62 million -2.7%6.6%4.3 $42.63
8/15/202510,790,000 shares $472.39 million -6.8%6.8%5.6 $43.78
7/31/202511,580,000 shares $497.71 million -10.2%7.5%6.5 $42.98
7/15/202512,890,000 shares $541.38 million -8.8%8.3%7.6 $42.00
6/30/202514,140,000 shares $558.67 million -0.6%9.1%8 $39.51
6/15/202514,230,000 shares $506.45 million -4.1%9.2%8.4 $35.59
5/31/202514,840,000 shares $499.22 million -2.8%9.6%8.9 $33.64
5/15/202515,270,000 shares $503.76 million +4.4%9.8%9.3 $32.99
4/30/202514,630,000 shares $449.29 million +0.6%9.5%8.4 $30.71
4/15/202514,550,000 shares $412.93 million +9.1%9.4%8.3 $28.38
3/31/202513,340,000 shares $402.47 million +4.1%8.6%7.7 $30.17
3/15/202512,810,000 shares $422.22 million -0.3%8.3%7.8 $32.96
2/28/202512,850,000 shares $426.49 million +1.4%8.3%7.8 $33.19
2/15/202512,670,000 shares $393.28 million +4.5%8.2%7.7 $31.04
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1/31/202512,120,000 shares $386.63 million +18.4%7.9%7.9 $31.90
1/15/202510,240,000 shares $340.07 million -6.1%7.0%7.1 $33.21
12/31/202410,900,000 shares $381.06 million +3.5%7.5%7.8 $34.96
12/15/202410,530,000 shares $385.50 million +0.8%7.2%7.1 $36.61
11/30/202410,450,000 shares $373.38 million -5.4%7.2%6.1 $35.73
11/15/202411,050,000 shares $379.46 million +2.9%7.6%6.5 $34.34
10/31/202410,740,000 shares $412.31 million +8.8%7.4%7 $38.39
10/15/20249,870,000 shares $373.48 million -6.3%6.8%6.3 $37.84
9/30/202410,530,000 shares $421.83 million -0.8%7.2%6.6 $40.06
9/15/202410,610,000 shares $447.64 million +4.4%7.3%6.4 $42.19
8/31/202410,160,000 shares $484.43 million +2.6%7.6%6.8 $47.68
8/15/20249,900,000 shares $461.98 million +4.7%7.4%8 $46.67
7/31/20249,460,000 shares $467.89 million +1.0%7.0%7 $49.46
7/15/20249,370,000 shares $445.73 million -1.6%7.0%7.2 $47.57
6/30/20249,520,000 shares $453.72 million +10.1%7.1%7.8 $47.66
6/15/20248,650,000 shares $351.62 million +0.6%6.5%7.5 $40.65
5/31/20248,600,000 shares $323.10 million -0.4%6.4%8.3 $37.57
5/15/20248,630,000 shares $338.38 million -1.4%6.4%7.9 $39.21
4/30/20248,750,000 shares $361.03 million -8.2%6.5%8.1 $41.26
4/15/20249,530,000 shares $395.97 million +0.1%7.1%8.9 $41.55
3/31/20249,520,000 shares $412.69 million -1.6%7.1%8.2 $43.35
3/15/20249,670,000 shares $411.46 million +6.2%7.2%8.1 $42.55
2/29/20249,110,000 shares $411.86 million +0.6%6.8%7.4 $45.21
2/15/20249,060,000 shares $410.24 million +7.2%6.8%7.4 $45.28
1/31/20248,450,000 shares $434.25 million -1.1%6.0%7.5 $51.39
1/15/20248,540,000 shares $457.23 million +3.6%6.1%7.4 $53.54
12/31/20238,240,000 shares $416.86 million -3.7%5.9%7.5 $50.59
12/15/20238,560,000 shares $425.43 million -11.8%6.1%7.3 $49.70
11/30/20239,700,000 shares $479.86 million -0.4%6.9%8.7 $49.47
11/15/20239,740,000 shares $484.76 million +0.4%7.0%9.4 $49.77
10/31/20239,700,000 shares $429.42 million +6.2%6.9%9.6 $44.27
10/15/20239,130,000 shares $438.06 million -1.8%6.5%9 $47.98
9/30/20239,300,000 shares $421.85 million -0.9%6.6%9.2 $45.36
9/15/20239,380,000 shares $402.50 million +1.0%6.7%10.1 $42.91
8/31/20239,290,000 shares $374.11 million -3.7%6.6%9.7 $40.27
8/15/20239,650,000 shares $386 million +4.8%6.9%7.9 $40.00
7/31/20239,210,000 shares $381.57 million +4.0%6.6%7.3 $41.43
7/15/20238,860,000 shares $376.37 million +2.8%6.4%7 $42.48
6/30/20238,620,000 shares $353.68 million -0.8%6.2%7.2 $41.03
6/15/20238,690,000 shares $362.29 million +33.3%6.2%7.2 $41.69
5/31/20236,520,000 shares $266.67 million -8.3%4.7%5.5 $40.90
5/15/20237,110,000 shares $257.67 million No Change5.1%7.3 $36.24
10/31/20226,860,000 shares $303.21 million -2.0%4.9%6.9 $44.20
10/15/20227,000,000 shares $324.52 million -3.5%5.0%6.9 $46.36
9/30/20227,250,000 shares $320.67 million +6.6%5.2%7.4 $44.23
9/15/20226,800,000 shares $322.93 million +9.2%4.9%7.1 $47.49
8/31/20226,230,000 shares $264.90 million -7.7%4.5%6.8 $42.52
8/15/20226,750,000 shares $299.77 million +10.7%4.8%7.2 $44.41
7/31/20226,100,000 shares $229.12 million +0.5%4.4%6 $37.56
7/15/20226,070,000 shares $238.61 million +5.9%4.3%6.1 $39.31
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6/30/20225,730,000 shares $212.12 million +1.4%4.1%5.3 $37.02
6/15/20225,650,000 shares $195.89 million -5.7%4.5%5.1 $34.67
5/31/20225,990,000 shares $218.75 million -16.1%4.3%5.5 $36.52
5/15/20227,140,000 shares $257.61 million +9.2%5.1%6.6 $36.08
4/30/20226,540,000 shares $240.41 million -12.2%4.7%6.1 $36.76
4/15/20227,450,000 shares $305.23 million +3.9%5.3%6.5 $40.97
3/31/20227,170,000 shares $265.58 million -1.7%N/A0 $37.04
3/15/20227,290,000 shares $238.38 million -4.1%5.2%6.6 $32.70
2/28/20227,600,000 shares $253.69 million -18.7%5.4%6.2 $33.38
2/15/20229,350,000 shares $314.72 million -1.8%6.7%7.2 $33.66
1/31/20229,520,000 shares $302.74 million +31.9%6.8%7.7 $31.80
1/15/20227,220,000 shares $238.84 million -1.5%N/A0 $33.08
12/31/20217,330,000 shares $223.05 million -0.8%5.3%6.4 $30.43
12/15/20217,390,000 shares $229.90 million +8.2%5.3%6.6 $31.11
11/30/20216,830,000 shares $181.00 million +10.3%4.9%6.4 $26.50
11/15/20216,190,000 shares $202.97 million -10.4%4.4%6.4 $32.79
10/29/20216,910,000 shares $220.22 million +1.9%5.0%7.5 $31.87
10/15/20216,780,000 shares $237.98 million +2.1%4.9%7.4 $35.10

IONS Short Interest - Frequently Asked Questions

Short interest is the volume of Ionis Pharmaceuticals shares that have been sold short but have not yet been closed out or covered. As of September 15th, traders have sold 20,890,252 shares of IONS short. 12.80% of Ionis Pharmaceuticals' shares are currently sold short. Learn More on Ionis Pharmaceuticals' current short interest.

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. IONS shares currently have a short interest ratio of 5.2. Learn More on Ionis Pharmaceuticals's short interest ratio.

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. 12.80% of Ionis Pharmaceuticals' floating shares are currently sold short.

Ionis Pharmaceuticals saw a drop in short interest in September. As of September 15th, there was short interest totaling 20,890,252 shares, a drop of 0.2% from the previous total of 20,924,638 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.

12.80% of Ionis Pharmaceuticals' shares are currently sold short. Here is how the short interest of companies in the industry of "biotechnology" compare to Ionis Pharmaceuticals: Roivant Sciences Ltd. (5.49%), BioNTech SE Sponsored ADR (1.14%), Insmed, Inc. (5.05%), Incyte Corporation (5.88%), United Therapeutics Corporation (7.14%), Genmab A/S Sponsored ADR (0.80%), Exelixis, Inc. (10.94%), Ascendis Pharma A/S (10.59%), Summit Therapeutics PLC (31.21%), BridgeBio Pharma, Inc. (12.85%),

As of the most recent reporting period, the following stocks had the largest short interest positions: SPDR S&P 500 ETF Trust ($75.21 billion), Invesco QQQ ($46.31 billion), iShares Russell 2000 ETF ($27.98 billion), SPDR S&P Biotech ETF ($11.59 billion), Nebius Group N.V. ($9.70 billion), Canadian Natural Resources Limited ($9.42 billion), iShares 20+ Year Treasury Bond ETF ($8.70 billion), iShares iBoxx $ High Yield Corporate Bond ETF ($8.53 billion), iShares iBoxx $ Investment Grade Corporate Bond ETF ($7.79 billion), and Financial Select Sector SPDR Fund ($7.74 billion). View all of the most shorted stocks.

Short selling IONS is an investing strategy that aims to generate trading profit from Ionis Pharmaceuticals as its price is falling. IONS shares are trading up $1.80 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.

A short squeeze for Ionis Pharmaceuticals 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 IONS, which in turn drives the price of the stock up even further.

Short interest is typically published by a stock exchange once per month. However, NASDAQ publishes a report for U.S. stocks, including IONS, twice per month. The most recent reporting period available is September, 15 2026.

Understanding short interest metrics can help you assess how traders are positioning around a stock like IONS:

  • Shares Sold Short: The total number of shares that have been sold by short sellers but have not yet been covered or closed out. A high number may indicate bearish sentiment.
  • Short Float: The percentage of a company’s publicly available shares (or "float") that are sold short. A higher short float suggests a greater portion of the stock is being bet against.
  • Days to Cover (Short Interest Ratio): This estimates how many days it would take short sellers to cover their positions, based on average daily trading volume. Higher values can signal potential for a short squeeze if buying pressure increases.

These metrics are often used by traders to gauge sentiment, volatility risk, and the potential for price movements based on short covering activity.


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Short Interest Tools

Short interest data for NASDAQ:IONS is sourced from the Financial Industry Regulatory Authority (FINRA), with the most recent report published on 10/9/2026. FINRA publishes updated short interest twice a month.
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