128 Years of Dow Components

Wish I could claim credit for this one...

http://money.cnn.com/interactive/investing/dow-timeline/

Despite what appears to be an error, this is a very good interactive graphic where one can roll-over to see changes in the US Dow Jones Industrial Average index since 1884 until now.  Lots of lessons likely to be learned (or unlearned) from this.

I've read it before, but a quick glance shows that no companies have stayed in the index since it was founded.  It is also interesting to see the small number of financial companies in the index until the 1990s.

Some observations:

• There appears to be an error in this chart.  Johns-Manville, formerly an asbestos manufacturer, is listed as a financial company, but should probably be classified as an industrial (see http://en.wikipedia.org/wiki/Johns_Manville). 
• The Dow's first financial constituent was in 1928 (not too long before the 1929 crash)
• Between 1928 and 1981 there were no financial companies included in the index.  American Express was added in 1982 and remains until today. JP Morgan was added almost a decade later in 1991.  There are now four financial constituents of the Dow (The Travelers Companies, Bank of America, JP Morgan Chase, and American Express)
• The first technology company, AT&T, was added in 1916, removed in 1928, and added back in 1939.  Other early technology companies included in the index were NCR (1929-1932), and IBM (1932-1938, added back in 1979).  There are now seven in the 30 stock index. 
• The first health care company, Merck was added in 1979.  It is still there, along with three others - United Health Group, Pfizer Incorporated, and Johnson & Johnson. 
• General Electric has been in the index the longest. Since 1907

Like most big cap indexes the Dow is essentially a momentum based index.  It comprises the biggest companies around.