What it is:
Market depth refers to a security's ability to tolerate the execution of large market orders without having a large effect on the security's price.
How it works (Example):
Also called depth of market, market depth measures the number of units that must be traded before a stock or bond's price moves. A security's market depth is a function of the proportion of buy orders to sell orders and the liquidity of the issuing company.
For example, a stock with similar numbers of outstanding buys and sells at a given time has greater market depth than a stock with lopsided numbers of buys and sells.