In a flash order transaction, buy or sell orders are shown to a collection of high-frequency traders for just 30 milliseconds before they are routed to everyone else. They are widely considered to give the few investors with access to the technology an unfair advantage, even by some of the marketplaces that offer the flash orders for a fee.

In the past, NASDAQ has defended flash orders.

While markets are supposed to ensure transparency by showing orders to everyone simultaneously, flash orders are currently allowed because of a loophole in securities regulations that allows for immediate trades.

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