The term Market-on-Open refers to broker instructions to buy or sell securities at their market price and at the beginning of the trading day. Unless trading is halted on a security, a Market-on-Open order will be executed once trading starts for the day.
While an At-the-Opening instruction can be combined with a limit order, a Market-on-Open (MOO) instructs the broker to purchase shares at the prevailing market price once trading on an exchange begins. This type of order cannot be executed at any other time during the day.
A MOO on the NASDAQ can be placed, amended, or canceled anytime from 7:00 a.m. Eastern Standard Time (EST) until two minutes before the opening bell (9:28 a.m. EST). MOO activity typically increases during the earnings season, when companies are reporting their quarterly results. Many companies make earnings announcements following the market's close. If the company's earnings exceed the market's expectations, the price per share of the company's stock may increase the following trading day.
As is the case with all market orders, execution is guaranteed; however, the price paid for the security is not guaranteed.
All-or-None, Fill-or-Kill, Good-Til-Canceled, Immediate-or-Cancel, National Best Offer, National Best Bid, market order, limit order, day order, One-Triggers-the-Other, One-Cancels-All, Good-Til-Date, At-the-Opening, Market-on-Close, At-the-Close, Market-if-Touched, Trailing If-Touched