High-Frequency Trading: technology, business, Illegal practices, and more High-frequency trading (HFT) firms use sophisticated computer programs to execute thousands of trades in a second. In fact, a second is slow by HFT standards: Traders often measure time by microseconds, or one-millionth of a second. In the decade or so since this high-tech form of trading zoomed onto the Wall Street scene, it's generated plenty of controversy. ...