What is Short Interest?
Short interest is simply the total number of shares of a particular company that have been sold short. Short interest figures are available toward the end of each month in financial publications like Barron's and the Investor's Business Daily, as well as online.
The significance of short interest is relative. If a company has 200 million shares outstanding and trades 12 million shares a day, a short interest of 6 million shares is most likely not significant. A short interest of 4 million for a company with 11 million shares outstanding trading only 100,000 shares a day is quite high and can raise the risk of shorting.