Market Depth

Market depth refers to the quantity of buy and sell orders waiting at different price levels for a given security. Deep markets have substantial order volume on both sides of the order book, meaning large trades can be executed without significantly moving the price. Shallow markets have thin order books, where even moderate trades can cause significant price impact. Market depth is visualized through the Level 2 order book, depth charts (which plot cumulative bid and ask volume against price), and heat maps. Depth is a key component of liquidity: a stock might have a tight bid-ask spread (good quote quality) but shallow depth (unable to absorb large orders without price impact). Blue-chip stocks like Apple typically have millions of shares in the order book near the current price, providing exceptional depth. Small-cap or thinly traded stocks may have only a few thousand shares, making them vulnerable to sharp moves on relatively small orders. Market makers and high-frequency traders contribute significantly to displayed market depth.