On May 6, 2010, stock prices in the United States jerked down and up with incredible speed. Within about five minutes, the Dow Jones Industrial Average plummeted about 600 points, only to regain most of that by a little later in the afternoon. Federal regulators later determined that this "flash crash" was triggered and then exacerbated by automated orders placed by mutual funds and other high-frequency traders. Stock exchanges had to cancel huge numbers of erroneous trades made during the crash.

Even before analysts began to understand what had gone wrong, some firms were able to stay out of the fray through real-time data analysis. For example, the high-frequency trading firm PhaseCapital, based in Boston, made no erroneous trades—an achievement that it credits to its use of complex event-processing software called StreamBase.