One of the world's leading experts on high-speed trading said Tuesday's market disruption following a bogus tweet from a hacked AP Twitter account didn't happen quite the way almost everyone thinks it did.
(Read More: Was Fake AP Tweet a Criminal Act?)
Eric Hunsader of the analysis firm Nanex said he has concluded that the market selloff didn't begin until about 17 seconds after the AP tweet hit the system at about 1:07:50 p.m. ET. But news usually drives algorithmic computer trading in milliseconds, rather than 10 seconds, after an event, he said.
Very few people outside Wall Street trading firms know how the super-secret algorithms are programmed, but Hunsader's educated guess is that the algorithms didn't trade on the single tweet from the AP. Instead, he surmised, they picked up on the volume of re-tweets of the initial report and were particularly sensitive to re-tweets from highly influential people with legions of followers.
He said another possibility is that the hoax AP Tweet may have put the trading computers into a kind of cyber high alert, and when an unusually large sale hit the market inside that time frame they all reacted at once.
Of course, a 17-second delay raises yet another possibility: Human beings were to blame after all.
—By CNBC's Eamon Javers; Follow him on Twitter: