Specialist Mike Pistillo, left, and trader Gregory Rowe work Thursday...

Specialist Mike Pistillo, left, and trader Gregory Rowe work Thursday on the floor of the New York Stock Exchange, where stocks rose in early trading Monday as Facebook shares fell. (May 17, 2012) Credit: AP

Forget Facebook. This is still Apple's stock market.

Apple -- the world's most valuable company -- climbed nearly 6 percent Monday, helping propel major U.S. stock indexes to gains after a week of losses. The Standard & Poor's 500, where Apple accounts for 4 percent of the index, enjoyed its best day in nearly five weeks. The Nasdaq composite index, where Apple accounts for an even heftier 12 percent, notched its biggest gain of the year.

And it was no thanks to Facebook. The social networking giant, on its second day as a public company, plunged 11 percent to $34.03.

Apple is no stranger to fickle investors. Its stock soared 57 percent from the end of last year through April 9, climbing above $636 from $405 as iPhone sales seemed unstoppable. Then it fell for most of April and May, declining to about $530 on Friday, partly because investors are worried phone companies will grow tired of subsidizing the expensive phones to sell to customers.

But Monday's gain of $30.90 to $561.28 came after several analysts said they expect its iPhone business to continue to do well.

The Dow Jones industrial average rose 135.10 points to 12,504.48. The S&P 500 rose 1.60 percent to 1,315.99, and the Nasdaq jumped 2.46 percent to 2,847.21.

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