Glossary / Market structure

Short interest

Short interest is the number of a security's shares that have been sold short and not yet bought back. It is usually quoted as a percentage — of shares outstanding, or of float, which produces a higher figure for the same position.

How it is measured

US exchanges collect short positions from member firms on scheduled settlement dates and publish the aggregate, historically twice a month. The figure is compiled as of a specific date and published after a lag of several business days, so the number in circulation always describes a position that existed some time ago.

Why it matters

Short interest describes the size of the position that has to be closed by buying, which is why it is tracked alongside volume: a large position relative to typical daily trading takes many sessions to unwind. Two cautions matter. The reporting lag means the figure can be badly stale during exactly the fast-moving periods when traders look at it. And a large position is not evidence of a coming move in either direction — some of it is hedging against convertible bonds or options books rather than a directional view.

In Market Census

Short interest is not one of the six factors in Market Census's composite score.

Related

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How Market Census scores stocks

Related terms

Days to cover
Days to cover is short interest divided by average daily trading volume.
Short squeeze
A short squeeze describes a sequence in which a rising price forces holders of short positions to close them, and closing a short position requires buying — which adds to the buying pressure that is already pushing the price up.
Float
Float is the number of a company's shares that are actually available to trade in the open market.
Volume
Volume is the number of shares that changed hands over a period.

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General information about market vocabulary, written to be descriptive rather than prescriptive. Not investment advice — see the risk disclosure.