1980: Market guru Joe Granville signals his 1,500 premium subscribers (who pay an extra $500 annually for his market-timing telephone alerts) to buy stocks. The next day, the Dow Jones Industrial Average surges 4% to close at 789.85. "I don't think that I will ever make a serious mistake on the stock market for the rest of my life," crows Granville — who freely admits he doesn't even invest his own money in stocks. Perhaps not; but listening to Granville's advice is a very serious mistake indeed: Financial newsletter expert Mark Hulbert later calculates that Granville's followers lose 98% of their money following his market calls between 1980 and 1987.

"The Prophet of Profits," Time Magazine, September 15, 1980, p. 69;John R. Dorfman, "One Fallen Guru Is Rising Again," The Wall Street Journal, July 28, 1989, p. C1;Robert J. Shiller, Irrational Exuberance (Princeton University Press, Princeton, NJ, 2000), p. 82

1970: The Dow Jones Industrial Average drops by 1.3% to 762.61, and H. Ross Perot suffers the worst one-day personal investment loss then on record. His Electronic Data Systems Corp. drops from roughly $150 a share to around $80 in chaotic over-the-counter trading, a paper loss of $450 million for Perot.

John Brooks, The Go-Go Years (Weybright & Talley, New York, 1973), pp. 1, 2, 21-24