Used for listed equity securities. Too many market orders of one kind-buy or to sell or limit orders to buy up or sell down, without matching orders of the opposite kind. An imbalance usually follows a dramatic event such as a takeover, research recommendation, or death of a key executive, or a government ruling that will significantly affect the company's business. If it occurs before the stock exchange opens, trading in the stock is delayed. If it occurs during the trading day, the specialist halts and then suspends trading (with floor governor's approval) until enough matching orders can be found to make an orderly market.