By Bill Rigby
Oct 28 (Reuters) - Apple Inc's profit and margins slid despite selling 33.8 million iPhones in its September quarter, prompting a brief but sharp selloff as disappointed investors cashed in some of the stock's recent strong gains.
Wall Street had hoped for a stronger beat on quarterly sales after the company predicted in September that its revenue and margins would come in at the high end of its own forecasts.
CEO Tim Cook predicted a "really great" holiday shopping season in a conference call with analysts, a crucial time for Apple as its new iPads go up against Amazon.com Inc's Kindle Fire and its new iPhones compete with lower-cost gadgets made by Samsung Electronics and other rivals using Google Inc's Android software.
Sources have said demand for Apple's cheaper, brightly hued iPhone 5C lagged demand for the top-tier iPhone 5S, spurring concerns about the iPhone's market positioning and its ability to compete with a growing profusion of lower-cost rivals.
Cook did not address the popularity of the 5C on his call with analysts but said there was "a very significant backlog" for the cutting edge 5S.
The world's most valuable tech company said on Monday it expected revenue of $55 billion to $58 billion this quarter, outpacing Wall Street's forecast for about $55.65 billion.
Gross profit margin for the fourth quarter was 37 percent, down from 40 percent a year ago as intense competition from the likes of Samsung Electronics took a toll. That was roughly level with analysts' average 36.9 percent forecast.
"We would have expected higher gross margins," said Morningstar analyst Brian Colello. "With the higher price phones and clear preference toward the 5S, we were all expecting more of a gross margin boost for the December quarter."
Shares in Apple, which have gained 17 percent since its upbeat forecast last month, slid as much as 5 percent on Monday before recovering after Cook said the company will continue studying its capital-return program, addressing recent demands by investors to share more of its cash hoard.
The stock was roughly flat at about $529 after hours, after gaining 0.7 percent in regular Nasdaq trading.
Beyond the holiday quarter, investors still hold out hope that the company that upended the cellphone industry and popularized tablet computing can again dream up a revolutionary device, returning Apple to the stellar growth of past years.
The company is increasingly hard-pressed to fend off rivals. Research house Strategy Analytics estimated on Monday that Apple's market share slipped to 13.4 percent in the calendar third quarter from 15.6 percent previously, while Samsung led the market with 35.2 percent.
As growth tapers off, some shareholders have become increasingly aggressive at seeking a bigger return of cash - the company ended the September quarter with $146.8 billion in cash plus short-term and long-term marketable securities.
Billionaire Carl Icahn, who owns 4.7 million Apple shares, has led the charge, demanding the company initiate a tender offer to buy back $150 billion of its stock.
Cook told analysts the company will continue to seek shareholder input on its capital return program, and will announce any changes in the first part of the new calendar year.
Apple said it sold 33.8 million iPhones last quarter, roughly in line with analyst expectations for 33 million to 36 million.
It sold 14.1 million iPads during the quarter, up very slightly from 14 million in the year-ago quarter, and moved 4.6 million of its Mac computers, down from 4.9 million a year ago.
Overall revenue was $37.5 billion, ahead of Wall Street's average forecast of $36.8 billion, according to Thomson Reuters I/B/E/S.
Earnings per share slid for the third straight quarter to $8.26, ahead of analysts' average estimate of $7.94.
"They had already preannounced and people got euphoric in recent weeks. It wasn't a massive blowout," said Shannon Cross of Cross Research.