Short interest

Short interest is the total number of a stock's shares currently sold short and not yet bought back to close the position. It is typically reported as a raw share count and also expressed as a percentage of the stock's float, the shares available for public trading, giving a sense of how much of the tradable supply is currently being bet against.

Short interest data is reported on a set schedule by FINRA, based on figures brokers submit, so the numbers investors see reflect positions as of a specific reporting date rather than a real time count. A rising short interest figure over time indicates that short sellers are building up bearish bets against the stock, while a falling figure suggests they are covering, buying to cover and closing out existing short positions.

Short interest by itself does not say much without context, what matters is short interest relative to the stock's trading volume, which is exactly what days to cover measures. A stock with high short interest and low trading volume has a large short position that would take a long time to unwind, setting up the conditions for a potential short squeeze if the price starts moving against the short sellers. Investors watch short interest trends both as a sentiment indicator and as a way to gauge how crowded a bearish trade has become.