We've just marked the third anniversary of the Flash Crash of 2010.
That May afternoon was already a down day for the Dow, with the index off by about 300 points since trading opened. Then, at 2:45 p.m., the Dow rapidly plunged by another 600 in just five minutes. By 2:47 p.m., the Dow had lost a staggering 998.5 points.
By 3:07 p.m., the losses had reversed and the Dow picked up most of those 600 lost points. In just about 20 minutes, the Dow had lost close to 9% of its total value - and then regained it.
But those 20 minutes were a virtual eternity, during which nearly $1 trillion in market value essentially disappeared.