May 26, 1896: The Dow Jones industrial average makes its debut, consisting of the stocks of 12 companies: American Cotton Oil, American Sugar Refining Co, American Tobacco, Chicago Gas, Distilling & Cattle Feeding Co, General Electric Co, Laclede Gas Light Co, National Lead, North American Co, Tennessee Coal, Iron & Railroad Co, U.S. Leather (preferred) and U.S. Rubber. Of the original 12, only GE remains in the average.
April 1, 1901: U.S. Steel Corp, a consolidation of several steelmakers and the largest company in the nation at the time, joins the Dow. It was removed May 6, 1991.
Nov. 7, 1907: A buyout of Tennessee Coal, Iron and Railroad Co by U.S. Steel is completed, marking the only instance in which two current constituents of the Dow combine. General Electric replaces Tennessee Coal after having been removed twice from the average.
1916: The industrial average expands to 20 stocks. It was expanded again in 1928, to 30, where it still stands.
Oct. 1, 1928: Standard Oil Co (New Jersey), an umbrella for John D. Rockefeller’s oil operations, joins the Dow. Standard Oil of New Jersey became Exxon Corp in 1972 and Exxon’s name changed to Exxon Mobil Corp in 1999, following an acquisition of Mobil Corp.
1928: The Dow begins being calculated with a special divisor rather than simply dividing by the number of stocks. This is to avoid distortions when constituent companies split their shares or when one stock is substituted for another. The index, though, is still called the average.
Oct. 28-29, 1929: The Dow falls 23 percent over the two days in the market’s most-known crash. The 12.8 percent fall on Oct. 28 marks the average’s second-worst daily percentage loss in its history. Oct. 19, 1987, stands as the worst. On Oct. 29 1929, the Dow fell another 11.7 percent. The days are known as Black Monday and Black Tuesday.
May 26, 1932: International Business Machines Corp joins the Dow. It was removed in 1939, but added back in 1979.
July 3, 1956: After 17 years and three months without a change in the average - the longest streak without a change - International Paper is added.
Nov. 14, 1972: Dow posts first close above 1,000.