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Pacific Biosciences of California (PACB) Short Interest Ratio & Short Volume

Pacific Biosciences of California logo
$1.26 +0.08 (+6.30%)
As of 01:53 PM Eastern
This is a fair market value price provided by Massive. Learn more.
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Pacific Biosciences of California Short Interest Overview

As of April 30, 2026, Pacific Biosciences of California (PACB) had a short interest of 47.09 million shares sold short, representing 15.54% of the public float. This marks a 1.57% increase in short interest since the prior report. The short interest ratio (days to cover) is 7.0, meaning it would take 7.0 days of the average trading volume of 6.72 million shares to cover all short positions.

Current Short Interest
47,090,593 shares
Previous Short Interest
46,364,406 shares
Change Vs. Previous Month
1.57%
Dollar Volume Sold Short
$74.87 million
Short Interest Ratio
7.0 Days to Cover
Last Record Date
April 30, 2026
Outstanding Shares
310,602,000 shares
Short Percent of Float
15.54%
Today's Trading Volume
2,033,032 shares
Average Trading Volume
6,718,264 shares
Today's Volume Vs. Average
30%
Short Selling Pacific Biosciences of California?
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Short Interest ChartDays to Cover ChartShort Percent of Float Chart

PACB Short Interest Over Time

PACB Days to Cover Over Time

PACB Percentage of Float Shorted Over Time

Pacific Biosciences of California 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
4/30/202647,090,593 shares $74.87 million +1.6%15.5%7.04 $1.59
4/15/202646,364,406 shares $74.18 million +1.6%15.7%8.42 $1.60
3/31/202645,631,632 shares $60.01 million +10.3%15.5%8.41 $1.32
3/13/202641,388,621 shares $55.05 million +8.4%14.0%6.56 $1.33
2/27/202638,191,242 shares $64.16 million -1.9%13.0%7.14 $1.68
2/13/202638,916,811 shares $66.55 million +9.3%13.2%5.27 $1.71
1/30/202635,591,593 shares $80.44 million +1.4%12.1%4.25 $2.26
1/15/202635,091,747 shares $82.47 million +3.2%11.9%4 $2.35
12/31/202534,003,835 shares $63.59 million -0.8%11.5%5.31 $1.87
12/15/202534,259,532 shares $72.63 million +0.6%11.6%5.45 $2.12
11/28/202534,042,917 shares $78.64 million +1.4%11.6%3.08 $2.31
11/14/202533,569,699 shares $54.05 million +3.3%11.5%3.62 $1.61
10/31/202532,511,384 shares $76.08 million -5.8%11.1%2.86 $2.34
10/15/202534,510,000 shares $60.05 million -9.1%11.8%4.7 $1.74
9/30/202537,970,000 shares $48.60 million -16.6%N/A5.5 $1.28
9/15/202545,550,000 shares $54.66 million +22.7%N/A6 $1.20
8/31/202537,110,000 shares $48.61 million -12.0%12.7%4.6 $1.31
8/15/202542,170,000 shares $55.24 million +0.7%N/A4.7 $1.31
7/31/202541,870,000 shares $57.78 million -5.7%14.3%4.5 $1.38
7/15/202544,380,000 shares $63.91 million -6.3%N/A4.8 $1.44
6/30/202547,370,000 shares $58.74 million +19.5%16.2%5.1 $1.24
6/15/202539,640,000 shares $47.57 million -23.8%13.5%4.5 $1.20
5/31/202552,020,000 shares $51.37 million -8.7%19.5%6 $0.99
5/15/202556,950,000 shares $60.37 million +15.7%21.3%6.5 $1.06
4/30/202549,210,000 shares $54.62 million +4.3%N/A4.8 $1.11
4/15/202547,200,000 shares $59.94 million -13.6%17.7%4.4 $1.27
3/31/202554,600,000 shares $64.43 million +2.2%20.4%4.7 $1.18
3/15/202553,410,000 shares $65.16 million -13.8%20.0%4.9 $1.22
2/28/202561,980,000 shares $89.87 million -7.1%23.2%5.5 $1.45
2/15/202566,690,000 shares $123.38 million +10.4%25.0%6.1 $1.85
1/31/202560,400,000 shares $93.02 million -0.2%N/A5.7 $1.54
1/15/202560,540,000 shares $105.64 million +6.5%N/A6 $1.75
12/31/202456,850,000 shares $104.04 million +7.1%N/A5.8 $1.83
12/15/202453,060,000 shares $104.00 million -2.4%N/A5.7 $1.96
11/30/202454,380,000 shares $103.87 million +4.3%N/A5.6 $1.91
11/15/202452,140,000 shares $83.16 million +3.4%N/A5.5 $1.60
10/31/202450,410,000 shares $109.39 million +3.9%N/A5.8 $2.17
10/15/202448,540,000 shares $101.93 million -6.0%N/A5.9 $2.10
9/30/202451,640,000 shares $87.79 million +11.0%N/A5.7 $1.70
9/15/202446,530,000 shares $84.22 million -23.8%N/A4.9 $1.81
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8/31/202461,030,000 shares $83.61 million +1.8%N/A6.8 $1.37
8/15/202459,960,000 shares $101.33 million +5.0%N/A6.8 $1.69
7/31/202457,100,000 shares $117.63 million -7.4%N/A5.9 $2.06
7/15/202461,680,000 shares $99.92 million +9.2%N/A6.2 $1.62
6/30/202456,470,000 shares $77.36 million +3.5%N/A5.3 $1.37
6/15/202454,570,000 shares $96.04 million +0.6%N/A5.3 $1.76
5/31/202454,250,000 shares $97.11 million -4.1%N/A5.2 $1.79
5/15/202456,580,000 shares $121.36 million +7.1%N/A5.2 $2.15
4/30/202452,820,000 shares $87.15 million +8.9%N/A5.1 $1.65
4/15/202448,520,000 shares $137.55 million -1.1%N/A5 $2.84
3/31/202449,050,000 shares $183.94 million +7.6%N/A5.6 $3.75
3/15/202445,570,000 shares $172.71 million +4.7%N/A5.4 $3.79
2/29/202443,540,000 shares $240.78 million +7.8%N/A5.3 $5.53
2/15/202440,380,000 shares $269.33 million +18.1%N/A5.4 $6.67
1/31/202434,190,000 shares $222.58 million -5.0%N/A5.1 $6.51
1/15/202436,000,000 shares $241.56 million -4.7%N/A5.6 $6.71
12/31/202337,780,000 shares $370.62 million +8.3%N/A6.7 $9.81
12/15/202334,890,000 shares $329.36 million +4.4%N/A6.7 $9.44
11/30/202333,430,000 shares $283.49 million -14.8%N/A7 $8.48
11/15/202339,230,000 shares $306.39 million +11.7%N/A8.5 $7.81
10/31/202335,120,000 shares $217.04 million -6.9%N/A8.1 $6.18
10/15/202337,740,000 shares $301.17 million +14.1%N/A9.6 $7.98
9/30/202333,070,000 shares $276.13 million -2.2%N/A8.6 $8.35
9/15/202333,820,000 shares $352.40 million +2.3%N/A9.4 $10.42
8/31/202333,060,000 shares $372.92 million +5.3%N/A9.3 $11.28
8/15/202331,390,000 shares $352.20 million +10.6%N/A8.3 $11.22
7/31/202328,390,000 shares $375.03 million -7.6%N/A7.7 $13.21
7/15/202330,710,000 shares $421.96 million -2.7%N/A8.6 $13.74
6/30/202331,550,000 shares $419.62 million +25.3%N/A8.8 $13.30
6/15/202325,190,000 shares $335.28 million -1.0%N/A6.7 $13.31
5/31/202325,440,000 shares $314.95 million +5.2%N/A6.7 $12.38
5/15/202324,180,000 shares $300.80 million -5.0%N/A6.6 $12.44
4/30/202325,440,000 shares $269.66 million -6.4%N/A6.7 $10.60
4/15/202327,180,000 shares $304.42 million +8.3%N/A6.6 $11.20
3/31/202325,100,000 shares $290.66 million -4.5%N/A5.8 $11.58
3/15/202326,280,000 shares $238.10 million +14.2%N/A6.2 $9.06
2/28/202323,020,000 shares $209.02 million +8.4%N/A5.6 $9.08
2/15/202321,240,000 shares $235.55 million -5.6%N/A5.3 $11.09
1/31/202322,490,000 shares $249.41 million -7.1%N/A5 $11.09
1/15/202324,200,000 shares $265.23 million -1.9%N/A4.9 $10.96
12/30/202224,670,000 shares $201.80 million +8.1%N/A5.1 $8.18
12/15/202222,820,000 shares $206.75 million +3.8%N/A4.4 $9.06
11/30/202221,990,000 shares $236.39 million -9.1%N/A3.9 $10.75
11/15/202224,190,000 shares $270.93 million +4.1%N/A4 $11.20
10/31/202223,240,000 shares $196.15 million -3.0%N/A3 $8.44
10/15/202223,950,000 shares $146.10 million -5.3%N/A3.1 $6.10
9/30/202225,290,000 shares $146.81 million -16.6%N/A3.3 $5.81
9/15/202230,310,000 shares $200.35 million +4.8%N/A3.8 $6.61
8/31/202228,930,000 shares $169.53 million -11.6%N/A3.6 $5.86
8/15/202232,720,000 shares $273.54 million -7.5%N/A3.9 $8.36
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7/31/202235,360,000 shares $154.52 million -1.9%N/A5.1 $4.37
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6/30/202241,020,000 shares $181.31 million +7.9%N/A5.7 $4.42
6/15/202238,010,000 shares $162.68 million +10.6%N/A5.3 $4.28
5/31/202234,370,000 shares $193.50 million +3.0%N/A5 $5.63
5/15/202233,370,000 shares $194.88 million +1.2%N/A5.2 $5.84
4/30/202232,960,000 shares $208.97 million +8.8%N/A5.5 $6.34
4/15/202230,290,000 shares $228.39 million -2.8%N/A5.2 $7.54
3/31/202231,170,000 shares $283.65 million +1.3%N/A5.6 $9.10
3/15/202230,760,000 shares $281.76 million +3.5%N/A6.3 $9.16
2/28/202229,710,000 shares $354.14 million +8.5%N/A6.6 $11.92
2/15/202227,390,000 shares $311.70 million +3.1%N/A6.3 $11.38
1/31/202226,580,000 shares $297.16 million +22.9%N/A7.1 $11.18
1/15/202221,630,000 shares $268.86 million +8.6%N/A6.9 $12.43
12/31/202119,910,000 shares $407.36 million -1.6%N/A7.8 $20.46
12/15/202120,230,000 shares $444.86 million +19.2%N/A9 $21.99
11/30/202116,970,000 shares $393.87 million -5.1%N/A8.5 $23.21
11/15/202117,890,000 shares $477.66 million +0.9%N/A9.6 $26.70
10/29/202117,730,000 shares $469.49 million +14.2%9.3%9.9 $26.48
10/15/202115,520,000 shares $378.53 million +9.3%8.2%8.5 $24.39
9/30/202114,200,000 shares $362.81 million +9.3%7.5%7.4 $25.55
9/15/202112,990,000 shares $359.04 million +2.4%6.8%6.6 $27.64
8/31/202112,690,000 shares $397.32 million +8.8%6.7%6.4 $31.31
8/13/202111,660,000 shares $343.62 million -2.1%6.1%5.7 $29.47
7/30/202111,910,000 shares $382.91 million -2.6%6.3%5.2 $32.15
7/15/202112,230,000 shares $330.21 million -10.5%6.5%5 $27.00
6/30/202113,660,000 shares $477.69 million -0.8%7.2%5.5 $34.97
6/15/202113,770,000 shares $385.84 million +0.8%7.3%5.2 $28.02
5/28/202113,660,000 shares $369.50 million -2.6%7.2%4.7 $27.05

PACB Short Interest - Frequently Asked Questions

Short interest is the volume of Pacific Biosciences of California shares that have been sold short but have not yet been closed out or covered. As of April 30th, investors have sold 47,090,593 shares of PACB short. 15.54% of Pacific Biosciences of California's shares are currently sold short. Learn More on Pacific Biosciences of California's 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. PACB shares currently have a short interest ratio of 7.0. Learn More on Pacific Biosciences of California'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. 15.54% of Pacific Biosciences of California's floating shares are currently sold short.

Pacific Biosciences of California saw a increase in short interest during the month of April. As of April 30th, there was short interest totaling 47,090,593 shares, an increase of 1.6% from the previous total of 46,364,406 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.

15.54% of Pacific Biosciences of California's shares are currently sold short. Here is how the short interest of companies compare to Pacific Biosciences of California: 10x Genomics (13.95%), Harvard Bioscience, Inc. (4.75%), Defiance Daily Target 2X Long LMND ETF (16.01%), Thermo Fisher Scientific Inc. (1.31%), Waters Corporation (3.50%), Agilent Technologies, Inc. (1.71%), Illumina, Inc. (4.46%), Mettler-Toledo International, Inc. (3.68%), Charles River Laboratories International, Inc. (7.04%), Bio-Techne Corp (8.63%),

As of the most recent reporting period, the following stocks had the largest short interest positions: SPDR S&P 500 ETF Trust ($86.09 billion), Invesco QQQ ($39.89 billion), iShares Russell 2000 ETF ($26.13 billion), Western Digital Corporation ($12.66 billion), Salesforce Inc. ($12.29 billion), Sandisk Corporation ($11.87 billion), SPDR S&P Biotech ETF ($9.82 billion), Lumentum Holdings Inc. ($8.51 billion), iShares 20+ Year Treasury Bond ETF ($7.76 billion), and Bloom Energy Corporation ($7.40 billion). View all of the most shorted stocks.

Short selling PACB is an investing strategy that aims to generate trading profit from Pacific Biosciences of California as its price is falling. PACB shares are trading up $0.04 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 Pacific Biosciences of California 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 PACB, 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 PACB, twice per month. The most recent reporting period available is April, 30 2026.

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

  • 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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This page (NASDAQ:PACB) was last updated on 5/21/2026 by MarketBeat.com Staff.
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