It's one day after the anniversary of the May 6, 2010, Flash Crash. That, of course, is the day that the Dow Jones Industrial Average went down nearly a thousand points. That included a plunge of about 600 points in a matter of minutes, followed by a nearly equal snapback in a similarly short period.
The Securities and Exchange Commission and Commodity Futures Trading Commission weighed in about six months afterward with an analysis tied to the initiation of a selling program by "a large fundamental trader," aka a mutual fund complex. This was an effort to sell 75,000 E-mini contracts as a hedge to an existing equity position. These were stock market index futures contract traded on the Chicago Mercantile Exchange's Globex electronic venue.