The Dow Jones Average that everyone keeps talking about even today started off as an index of stocks for 12 leading American companies – almost all of them dealing in commodities. Natural gas, coal, sugar, tobacco, steel – these were the companies leading the American economy in the 1890s, and the average dollar figure of their stocks made up the average of the Charles Dow index, printed daily in what became the Wall Street Journal. The average started off in the 40s; its movements up and down indicated the relative prosperity of the economy. Quick Dow drops were especially concerning.

On this day, December 12, in 1914, after a 4½ day suspension of trading at the outset of WW I, the Dow’s first day of reopening dropped the average from 71.42 to 54, the largest single-day drop in history.

Because the stock index was still in its infancy, that drop is usually disregarded in reviews of the largest single-day average drops. Although the “Black Friday” October 1929 crash that signaled the start of the Great Depression is widely considered to be the worst, at around 12% it was relatively mild compared to the“Black Monday” one in 1987. Black Monday, widely considered to be the worst crash in history, saw the Dow closing 22.61% down.