The flash crash was essentially over in five minutes. But it took regulators nearly five months to come up with a theory about what happened. And in late September 2010, when the SEC and the CFTC—the same agency now charging Sarao with causing the crash—released a joint report on what happened, they didn't mention spoofing, let alone Sarao. Instead, they blamed a large trade by a firm out of Kansas City.
It's not even clear that the feds' new explanation is correct. As Matt Levine notes over at Bloomberg View, regulators believe that Sarao continued to place massive fake sell orders in the years after the flash crash, but somehow that activity never triggered another crisis:
If regulators think that Sarao's behavior on May 6, 2010, caused the flash crash, and if they think he continued that behavior for much of the subsequent five years, and if that behavior was screamingly obvious, maybe they should have stopped him a little earlier?
Also, I mean, if his behavior on May 6, 2010, caused the flash crash, and if he continued it for much of the subsequent five years, why didn't he cause, you know, a dozen flash crashes?
So I mean…maybe he didn't cause the flash crash?
I thought it was computer programs having a skynet-ish meltdown.....gotta blame someone I guess.