Calculating the DJIA in the Early Days

• When founded in 1896, calculating the Dow Jones Industrial Average was fairly straightforward. In those days the listing contained 12 companies. Market officials added up the share price of each company and divided by 12. Over the next 40 years the DJIA was calculated this way every hour, on the hour. The value was released to stock brokers and investors through the Dow Jones News Service.
  
  

Calculating the DJIA Today

• Today the DJIA is calculated by computers and its' valuation is watched by investors around the world, in many cases in real time, as shares of companies trade hands from investor to investor. The formula starts the same way by totalling the value of the companies contained in the DJIA. From there it gets a little more complex. While calculating the value of the component stocks is the same, the divisor is always being adjusted. According to the Dow Jones website, the reason is "over the past hundred-plus years, there have been many stock splits, spin-offs and stock substitutions, without adjustment would distort the value of the Dow." As of March 14, 2010, the Dow Jones Divisor was 0.13231925. Every $1 change of a particular stock within the average, equates to a 7.56 point movement, according to the CME Group.
  
  

Oldest and Newest

• The oldest company contained in the Dow Jones Industrial Average is General Electric. Added to the DJIA on November 7, 1907, General Electric is represented on the ticker by the symbol GE. The most recent company to be included, at the time of writing, is Cisco Systems (CSCO), added on June 8, 2009.
  
  

Companies and Their Ticker Symbols

• The following companies comprise the Dow: 3M, MMM; Alcoa, AA; American Express, AXP; AT&T, T; Bank of America, BAC; Boeing, BA; Caterpillar, CAT; Chevron Corporation, CVX; Cisco Systems, CSCO; Coca-Cola. KO; DuPont, DD; ExxonMobil, XOM; General Electric, GE; Hewlett-Packard, HPQ; The Home Depot, HD; Intel, INTC; IBM, IBM; Johnson & Johnson, JNJ; JP Morgan Chase, JPM; Kraft Foods, KFT; McDonald's, MCD; Merck, MRK; Microsoft, MSFT; Pfizer, PFE; Procter & Gamble, PG; Travelers, TRV; United Technologies Corporation, UTX; Verizon Communications, VZ; Wal-Mart, WMT; Walt Disney, DIS.
  
  

Best and Worst Years

• In 1933 the DJIA posted a 66.69% increase year over year. However two years prior, it shed 52.67% of its value. More recently, in 1995 the DJIA posted a 33.45% increase, and in 2008 it lost 33.84%.