A crossed price occurs when the bid price exceeds the ask price in a market, creating an inverted spread that represents an immediate arbitrage opportunity. This unusual condition typically results from system errors, delayed price feeds, or temporary market inefficiencies across different trading venues or time zones.

Crossed prices are generally corrected quickly through automated trading systems or arbitrageurs who simultaneously buy at the lower ask price and sell at the higher bid price, capturing risk-free profit. These situations are rare in liquid markets with efficient price discovery mechanisms but may occur more frequently in less liquid instruments or during periods of extreme market volatility.

Real-world example: A stock shows a bid of $50.05 and ask of $50.02 due to a system delay, allowing a high-frequency trader to buy at $50.02 and immediately sell at $50.05 for a guaranteed $0.03 profit per share.