Dow Jones Industrial Average.

The Dow Jones Industrial Average (DJI on the New York Stock Exchange, pretty much DJIA everywhere else) was created by Wall Street Journal editor and Dow Jones & Company founder Charles Dow. He did it to gauge the performance of the industrial components of the stock market. It is the oldest continuing market index in the US.

When it was first published in May 26, 1896, the DJIA was computed at 40.94. On October 5, 2006, it stood at an all time high of 11,866.69.

It’s easy to see that the overall trend is increasing, but if you noticed between the periods of 1960 to mid 1980s, the value is pretty much constant. If you were unlucky enough to invest on December 11, 1914, you’d see your money lose 24.39% the very next day. The second largest decrease was on "Black Monday" in 1987, when the DJIA lost 22.6%.

Nevertheless, if you had invested $1 in 1896, you’d have $290 now.

Link [wiki] - via growabrain