1946: The S&P index plunges by 6.73%, leading the U.S. Securities and Exchange Commission to appoint an investigative task force that concludes that the crash was caused when believers in the Dow Theory of technical analysis all sold at once.

Merton H. Miller, "The Crash of 1987 and the Crash of 1946," in Eugene N. White, ed., Crashes and Panics: Lessons from History (DowJones Irwin, Homewood, IL, 1990), pp. 229-231;Robert J. Shiller, "Do Stock Prices Move Too Much to Be Justified by Subsequent Changes in Dividends?" in Richard H. Thaler, ed., Advances in Behavioral Finance (Russell Sage Foundation, New York, 1993), p. 145.

1929: On a sweltering 94-degree day, the steamy canyons of lower Manhattan are full of stock speculators back from the Labor Day hiatus. The Dow Jones Industrial Average peaks at 381.17, setting a new all-time high and closing up 27.1% for the year to date. Volume is a blistering 4.43 million shares. Radio Corp. of America, the hottest growth stock of them all, closes at $505 a share, up from $94.50 just 18 months earlier. Unfortunately, the Dow will not surpass this day's closing price for another quarter-century; it finally rises above 381.17 on November 23, 1954. When you hear about "stocks for the long run," do you realize how long "long" can be?

Phyllis S. Pierce, ed., The Dow Jones Averages 1885-1980 (DowJones Irwin, Homewood, IL, 1982), not paginated;Frederick Lewis Allen, Only Yesterday: An Informal History of the 1920s (John Wiley & Sons, New York, 1997, reprint of 1931 ed.), p. 240;John Brooks, Once in Golconda: A True Drama of Wall Street, 1920-1938 (Harper & Row, New York, 1969), p. 110

1728: Matthew Boulton is born near Birmingham, England, the son of a hardware dealer. Boulton later establishes the Soho Manufactory to produce buckles, buttons, Sheffield plate (silver-coated copperware) and copper coins for the Royal Mint and the East India Co. In 1768-1769 he becomes fascinated with James Watt's steam engine, uses it to power his factory, and soon forms a partnership with Watt to sell steam engines to other entrepreneurs (including Robert Fulton, father of the steamboat, and potter Josiah Wedgwood).