What is Short Interest?

Article Summary:

Short interest identifies how many investment shares are sold short for a particular stock, which reveals the general market’s sentiment towards that stock. The short interest ratio represents the number of days it takes for investors to cover their positions and rebuy a shorted share.

If you’ve invested in the stock market, you may have considered shorting a stock, or selling a borrowed share only to rebuy it after the price declines. Though risky, this investment strategy can be profitable if the price does decline. While it can be tricky to predict how a stock’s price will behave, a stock’s short interest can give you a better idea of what other investors believe will happen.

Short interest is the number of shares sold short, but not yet bought by the public in the open market. This can be a great representation of how investors feel about the overall market. Keep reading to learn more about what short interest is, what it can tell you about the market, and how it can affect your investments.

What is short interest?

Short interest is both an indication of market sentiment and a measure of how many shares from a stock, index fund, or investment security were sold short.

A high short interest indicates that a larger number of shares were sold short because investors predict a particular security’s price to decline. This suggests that the overall market sentiment is pessimistic about this stock.

IMPORTANT! A high short interest doesn’t necessarily mean the shares will decline in price. This is simply a representation of the number of investors that are betting it will decrease in price. In fact, extreme levels in short interest sometimes are a signal that traders are too bearish on a stock and a price reversal may occur soon.

How do you calculate a stock’s short interest?

Represented as a number or percentage, you can calculate short interest without much difficulty. You can determine short interest by dividing the number of sold shares by the number of shares the public can buy.

How short interest works

A stock’s short interest shows the number of investment security shares investors sold short and are pending purchase. With this in mind, it’s easy to see how short interest helps investors get ahead in the stock market.

Investors can use short interest to review an individual stock, a market index, or the overall stock market. Some investors may also short a stock to secure their long position.

So what is a short seller?

Short selling happens when an investor, also known as a short seller, borrows shares of an investment security from a brokerage or stock trading app and sells the borrowed stock with the expectation that the price will decline.

If the share price decreases, the short seller buys back the same shares at a lower price, profiting from the falling stock. The short seller then returns the borrowed investment to the lender.

Pro Tip

This type of investing involves substantial risk. If the price increases instead of decreasing, short sellers may need to buy back the shares at a higher price, leading to significant losses.

How do investors use short interest?

Let’s revisit individual investors for a minute. Investors can use short interest to assess market sentiment surrounding a particular stock, or the general market. It can help investors protect their assets, or prepare for losses.

Many traders consider intense levels of short interest as a contrarian indicator. Contrarian investing (often associated with short interest theory) happens when investors go against current market trends. For instance, an extremely high short interest could signify that investors have a more bearish sentiment about the market, and the price could go in the other direction.

What is a short interest ratio?

Short interest ratios, also known as the days-to-cover ratio, examine the number of shares in a company’s stock against the stock’s average trading volume. The short interest ratio illustrates how many days it may take for the stock’s shares to be covered or rebought.

A high short ratio coveys that investors are bearish about the market and expect the stock price will decrease. A low short ratio, on the other hand, indicates that

Determining the short interest ratio is a quick and easy calculation. You can calculate a stock’s short interest ratio by dividing the number of shorted shares by the average daily volume of shares traded each day.

The New York Stock Exchange short interest ratio

While it may appear to apply to a specific market, the NYSE short interest ratio can provide investors with an idea of the overall stock market’s sentiment. However, rather than calculating the short interest of a particular stock, the NYSE short interest ratio examines how quickly the entire market’s short position will be covered. Not only does this reveal investors’ sentiment about the NYSE, but it also reveals overall sentiment about the economy.

For instance, let’s say 6 billion shares were sold short over one month on the NYSE. During that month, the NYSE’s daily volume equaled about 3 billion. Using the above equation, we can estimate that it would take approximately two days to cover the NYSE’s short position.

How does short interest differ from short interest ratio?

Though they sound similar, a stock’s short interest and short interest ratio explain different market behaviors. While short interest represents the number or percentage of shares sold short, the ratio determines the number of days to cover those shares.

For example, if a stock has a high short interest and ratio, this means multiple investors tried to sell their shares short and are struggling to cover their short positions.

Limitations of using short interest

While the short interest can be a good market sentiment indicator, there are some limitations to using it.

  • Can’t always keep up with market changes. Despite the amount of data collected, most reports that brokerage firms rely on only update monthly or biweekly. The market moves a lot faster than this.
  • Not indicative of a trend. Though short interest can be a great indicator, it doesn’t tell you the full picture. For example, a stock may have many shorted shares without a decrease in price, or a stock may make a significant shift with no change in the short interest.

What does this mean for individual investors?

Though short interest can be a helpful market indicator, savvy investors usually don’t rely exclusively on these numbers. Short interest information can become irrelevant, especially in an erratic market, because brokerage firms only report it once or twice a month.

However, both short interest and short interest ratio are often overlooked by many investors and can be great tools regardless of whether you short sell stocks. Whatever your preferred investment strategy is, make sure to check out an individual stock’s short interest when reviewing monthly reports. It may reveal some valuable information.


What is a short squeeze?

A short squeeze occurs when many short sellers try to cut their losses and rebuy their borrowed shares. Short squeezes tend to happen because short sellers panic if the stock price rises. They are more likely to happen in smaller cap stocks, which have a limited supply.

In a short position, investors can lose a limitless amount of money because there is no restriction on how high a stock’s price can go. Since short selling can lead to potentially massive losses, short sellers try to quickly rebuy shares to cover their positions and avoid losing even more money.

Is a high short interest ratio good?

A high ratio isn’t great for a short seller, as this makes it difficult for traders to close their short position. It also makes the stock more susceptible to a short squeeze.

How do you tell if a stock is heavily shorted?

A stock is heavily shorted if the price increases and it has a high ratio. If a stock has a high short interest ratio, investors will take longer to cover their short positions.

What happens when a stock is heavily shorted?

Short sellers lose money when a stock is heavily shorted as the stock price rises. Investors try to buy back the shares to cover their losses (which may lead to a short squeeze).

What is a good short interest in stock?

This depends on what you mean by “good” short interest. A low short interest indicates that investors are generally optimistic about the stock in question, while a high short interest tends to indicate overall pessimism. However, a very high interest may also indicate a bullish or bearish market.

Key Takeaways

  • Short interest is often a good market sentiment indicator, as it tells investors how many shares of a particular stock have been sold short but not yet covered.
  • The short interest ratio calculates the average number of days it takes a short seller to cover their position.
  • If a stock’s price rises with a high short interest, this may lead to a short squeeze.
  • While short interest and short interest ratio are useful indicators for investors to use, they have several limitations. For instance, they are not always up-to-date and they may not tell the full picture of a stock.
View Article Sources
  1. Short Sale Volume and Transaction Data — U.S. Securities and Exchange Commission
  2. Staff Report on Equity and Options Market Structure Conditions in Early 2021 — U.S. Securities and Exchange Commission
  3. How To Invest In The Stock Market: 8 Basic Concepts — SuperMoney
  4. 24 Stock Trading Secrets From The Most Successful Investors — SuperMoney
  5. What Is Scalping In Trading? Strategies and Examples for Beginners — SuperMoney
  6. What is a Stock Float? Examples of High Vs. Low — SuperMoney
  7. Best Online Brokers for Stock Trading in 2022 — SuperMoney
  8. Best Stock Trading Apps in 2022 — SuperMoney
  9. Brokerages: Reviews & Comparisons — SuperMoney