The last time the index of general retailers dropped was in 1986.
On Thursday, the index had dropped a record 74.2 points in less than three hours.
Since the presidential election alone, the index has dropped 11.4 percent.
The index had dropped about 16 percent since the end of July.
By 1988, the last year for which complete statistics are available, the index had dropped to 33.
And no matter how low the national index dropped, a man's personal individual business was unaffected.
Almost as bad was the week ended May 17, 1940, when the index dropped 14.2 percent.
A regional economic index for Philadelphia also dropped much more than expected.
In all, the exchange's index dropped 15 percent this week.
The index has dropped 18.7 percent in the last 15 trading days.