CRASH OF '87: By The Numbers

The worst one-day crash in stock trading took place 25 years ago on October 19. Here's a look back at Black Monday, on its quarter-century anniversary.

SOURCES: Jeremy J. Siegel, Wharton School; Points and Figures; Securities Industry and Financial Markets Association, Wikimedia Commons

Opening value of the Dow Jones Industrial Average.

Closing value of the Dow.

The decline, which still ranks as the largest percentage drop in one day.

Loss of market value, in billions.

The amount of shares traded on the New York Stock Exchange, in millions.

The Dow on August 25, 1987.

The drop from August 25 to October 19.

Value of a S&P 500 stock index futures contract on August 25.

Value of a S&P 500 stock index futures contract on October 20.

The drop in value of that contract.

The discount of a S&P futures contract at midday October 20, compared to the reported spot index, an unprecedented event. Trading halted for the only time in history of trading in stock index futures contracts.

What the value of the Dow would have been at midday October 20, if the futures market had accurately reflected spot prices for stocks that Tuesday. It closed that day up slightly, at 1,841.

Points lost in the Dow at the trough of the Flash Crash, May 6, 2010.

The drop, at lowest point of Flash Crash.

Average daily volume of trading this year on the NYSE, through August, in millions of shares.