A halt in the trading of a particular stock due to excess volatility. A trading halt may occur when bad news, such as the announcement of regulatory investigations, imminent bankruptcy proceedings, or sharp earnings shortfalls seep into the market. Expectations of a merger transaction also may produce volatile situations and halt trading. The company may ask the exchange to halt trading or the exchange may do so of its own accord. Trading halts are temporary and last only until sell and buy orders begin to rebalance. Also called suspended trading.