SAN JOSE, Calif. — Shares of Apple Computer Inc. surged yesterday after the company reported its best quarterly profit ever, with revenue up 75 percent as sales of its iPod music player continue to be brisk.

Apple's shares rose $2.85, or 7.4 percent, to $41.09 in early trading yesterday on the Nasdaq Stock Market.

For its fiscal third quarter ended June 25, Apple's net income rose to $320 million, or 37 cents per share, up from the $61 million and 8 cents per share the company reported in the year-ago quarter.

Apple executives surprised some analysts by predicting that the company would not meet their expectations in the next quarter. For more than a year, Cupertino-based Apple has offered guidance that surpassed analyst expectations.

"It's been a long time since they guided down," said Shaw Wu, an analyst with American Technology Research. "It's kind of bizarre considering the September quarter is usually a strong back-to-school quarter for Apple."