Imbalance of Orders
A situation when too many orders of a particular type - either buy, sell or limit - for listed securities and not enough of the other, matching orders are received by an exchange. Also referred to as "order imbalance".
Investopedia Commentary
Shares experiencing an imbalance of orders may be temporarily halted if trading has already commenced for the day. If it occurs prior to market open, trading may be delayed. Better-than-expected earnings or other unexpected good news can result in a surge in buy orders in relation to sell orders. Likewise, unexpected negative news can bring a large sell-off.
Related Links
The Nitty-Gritty Of Executing A Trade
See also: Market on Close, Market Order, Trading Halt