Stock of iPhone maker Apple is added to the Dow; set to start trading in the index Thursday

The world's most valuable company is now a member of the Dow Jones industrial average.

Apple Inc. was added to the Dow after the market closed Wednesday. The Dow will begin trading with Apple stock when the markets open Thursday.

Created in 1896, the Dow is an index that tracks 30 stocks. It is meant to reflect the U.S. economy and markets.

The iPhone maker replaces AT&T, which was booted from the Dow. The manager of the index, S&P Dow Jones Indices, says it made the change because of a stock split of Visa, another Dow member.

Apple, based in Cupertino, California, has a market value of $748 billion. That's more than double the value of Exxon Mobil, a fellow Dow member and the world's second-most-valuable company.