A controversial computerized trading practice offered by some stock exchanges. Flash trading uses highly sophisticated high-speed computer technology to allow traders to view orders from other market participants fractions of a second before others in the marketplace. This gives flash traders the advantage of being able to gauge supply and demand and recognize movements in market sentiment before other traders.

Flash orders are also known as "step-up orders" or "pre-routing orders".

Flash orders have been subject to scrutiny because of the advantage they give traders who are able to participate in the orders. Flash trading has been compared to front running, and opponents believe that the practice is harmful to market transparency. Proponents of flash trading state that it is necessary to provide liquidity for exchanges.