The number of shares a seller is willing to sell at any given price.

Often this quantity is expressed in terms of hundreds of shares. Sometimes this figure is used to anticipate potential short term pressure on the price of the stock. While useful on exchanges such as NYSE and AMEX, it is not as helpful on the Nasdaq. This is due to the fact that it has market makers ready to buy and sell shares as opposed to specialists who balance books of buy and sell orders.