Apple (Nasdaq: AAPL), the world's most valuable technology company, introduced its iPhone 5, the successor to the best-selling iPhone 4S, on all three major U.S. carriers, AT&T Inc. (NYSE: T), the Verizon Wireless unit of Verizon Communications (NYSE: VZ) and Sprint-Nextel (NYSE: S).

Shares of Apple fell $3.63 to $656.96 during the introduction of the new phone at an invitation-only event in San Francisco. Apple, of Cupertino, Calif., introduced the iPhone 4S last Oct. 4, a day before the death of founding Chairman Steven P. Jobs.

The iPhone 5 is smaller, thinner and more versatile than its predecessor, as had been expected by industry analysts, engineers and devotees of the company. Weight: 112 grams, 20 percent less than the old iPhone.

The new model will use the A6 microprocessor from longtime supplier ARM Holdings (Nasdaq: ARMH) of the UK, which should make overall performance and graphics perform twice as fast as the iPhone 4S, company executives said. It will be able to switch among antenna connections to find the strongest connection, they added.