what is an opening imbalance only order oio 
opening imbalance only orders oio are a type of limit order that provides liquidity during the opening cross on the nasdaq a limit order is an order placed with a brokerage to execute a buy or sell transaction at a set number of shares and a specified limit price breaking down opening imbalance only order oio opening imbalance only oio orders are only executable on the opening cross and are not displayed or disseminated oio buy orders only execute at or below the 9 30 a m bid price while oio sell orders only execute at or above the 9 30 a m offer price oio orders must necessarily be limit orders and market oio orders are not permitted since oio orders are only executable during the opening cross they are not at risk of being executed prior to market open unlike continuous market orders 1 oio buy or sell orders priced more aggressively than the 9 30 a m nasdaq highest bid or lowest offer prior to market open will be re priced to the nasdaq bid or offer before the opening cross is executed 1 so for example if an oio buy order price is 9 95 and the nasdaq bid is at 9 93 the oio order will be re priced to 9 93 this adds liquidity to the market and helps ensure that market on open moo and limit on open loo orders are properly executed oio orders are accepted on the nasdaq from 7 a m onward however market participants cannot update these orders after 9 28 a m although new oio orders can still be entered after that time 2 nasdaqopening imbalance only orders oios are executed within the nasdaq nasdaq is a global electronic marketplace for buying and selling securities and also serves as the benchmark index for u s technology stocks the national association of securities dealers nasd created nasdaq to enable investors to trade securities on a computerized and transparent system in 2006 nasdaq officially separated from the nasd and began to operate as a national securities exchange 3 the term nasdaq is also used to refer to the nasdaq composite which is an index of more than 2 500 stocks listed on the nasdaq exchange that include some of the world s largest technology and biotech giants such as apple google microsoft oracle amazon intel and amgen nasdaq has been a leader in trading technology from its inception the nasdaq computerized trading system was initially devised as an alternative to the inefficient specialist system which had been the prevalent model for trading for nearly 100 years today due to rapid technological advancements nasdaq s electronic trading model is the standard for markets worldwide 