For a few surreal minutes, a mere 12 words on Twitter caused the world's mightiest stock market to tremble.
No sooner did hackers send a false Associated Press tweet reporting explosions at the White House on Tuesday than investors started dumping stocks - eventually unloading $134 billion worth.
Except most of the investors weren't human. They were computers, selling on autopilot beyond the control of humans, like a scene from a sci-fi horror film.
“Before you could blink, it was over,” said Joe Saluzzi, co-founder of Themis Trading and an outspoken critic of high-speed computerized trading. “With people, you wouldn't have this type of reaction.” For decades, computers have been sorting through data and news to help investment funds decide whether to buy or sell. But, that's old school. Now “algorithmic” trading programs sift through data, news, even tweets, and execute trades by themselves in fractions of a second, without slowpoke humans getting in the way. More than half of stock trading every day is done this way.