April 23 (Bloomberg) -- Apple Inc. reported a 36 percent jump in profit, topping estimates, on sales of Macintosh computers. The profit margin in the quarter and the forecast for the current period missed projections, sending the shares lower.

Second-quarter net income rose to $1.05 billion, or $1.16 a share, Cupertino, California-based Apple said today in a statement. The company forecast profit this quarter of $1 a share, missing the average estimate of $1.11 in a Bloomberg survey of analysts.

Apple sold 2.29 million Macs, spurred by demand for notebooks including the ultra-thin MacBook Air, unveiled by Chief Executive Officer Steve Jobs in January. The forecast raised concern that earnings growth may slow this year as consumers wait for a new version of the iPhone and an iPod price cut curbs profitability.

``The only fly in the ointment would appear to be the earnings guidance,'' said David Garrity, an analyst at Dinosaur Securities Inc. in New York. ``Investors are jumpy, if nothing else.''

Apple's profit forecast has now missed analysts' estimates in nine of the past 10 quarters. The company has topped its forecast in each quarter for the past two years.

Apple fell 58 cents to $162.31 in extended trading and declined as much as 4.9 percent. The shares closed at $162.89 at 4 p.m. New York time in Nasdaq Stock Market trading. They have gained 41 percent since dropping to an intra-day low of $115.44 on Feb. 26.

Sales Climb

Sales also beat analysts' projections, climbing 43 percent to $7.51 billion and surpassing the average estimate of $6.96 billion. Profit exceeded the average estimate of $1.06 a share. A year ago, Apple reported profit of $770 million, or 87 cents a share.

``Our U.S. business grew beautifully, rising 40 percent,'' Apple Chief Financial Officer Peter Oppenheimer said in an interview. ``Customers are loving the MacBook Air.''

Apple said it sold 10.6 million iPod media players and 1.7 million iPhones in the quarter. On average, analysts had estimated Apple sold 10 million iPods and 1.7 million iPhones, according to Piper Jaffray & Co. analyst Gene Munster in Minneapolis. Analysts projected Mac sales of about 2 million, Munster said.

The gross margin, or the percentage of sales left after deducting production costs, narrowed to 32.9 percent in the quarter. That missed the estimate of 35.8 percent by Bank of America Corp. analyst Scott Craig in New York.

Gross Margin

``The gross margin is definitely light,'' said Jane Snorek, who helps manage more than $70 billion in assets, including Apple shares, at First American Funds in Minneapolis. ``It's light compared to last quarter and light compared to last year.''

Apple said a price cut on the iPod Shuffle to $49 from $79, a decline in software revenue from its Leopard operating system, and a greater mix of low-profit sales of songs and movies on the iTunes store weighed on its margin.

Jobs unveiled the MacBook Air in January, pulling it out of a manila envelope on stage during a speech in San Francisco. At less than 1 inch (2.5 centimeters) thick with a 13.3-inch screen, the notebook is Apple's first so-called ultra-portable in a decade.

Notebooks sales have outsold desktops at Apple and its larger rivals Hewlett-Packard Co. and Dell Inc. In February, Jobs, 53, updated Apple's two other notebooks, the MacBook and MacBook Pro, with faster processors and larger hard drives.

IPhone Goal

Investors are also looking to the iPhone, the Web-surfing media phone that Apple began selling in June, to bolster earnings this year. Today, the company reiterated its goal of selling 10 million iPhones this year. It sold almost 4 million last year.

A shortage of iPhones in stores toward the end of the quarter occurred because people bought handsets to unlock them for use on unauthorized wireless networks, Apple said. A post- holiday drop in iPhone demand was not as big as projected, Chief Operating Officer Timothy Cook said.

``We sold more than we thought we would,'' Cook said on a conference call with analysts. The number of unlocked Phones is ``significant'' and a sign of pent-up demand worldwide for the device, he said. Apple, which sells the iPhone in the U.S., U.K., France, Germany, Austria and Ireland, plans to release the handset in more markets in Europe and in Asia this year.

Price Cuts

Apple's wireless partners in Europe cut the price of the iPhone this month, a sign that a new version may be announced as early as June, Munster and Sanford C. Bernstein & Co. analyst Toni Sacconaghi said.

The new iPhone is expected to offer faster downloads from the Internet over so-called third-generation wireless networks. AT&T Inc., the exclusive U.S. provider of iPhone service, has said it expects a 3G iPhone this year.

Separately, Apple agreed to buy closely held microprocessor designer P.A. Semi Inc., adding technology for low-power chips. Apple spokesman Steve Dowling confirmed the purchase and declined to comment on plans for P.A. Semi or terms of the deal. Forbes.com said Apple paid $278 million in cash, citing an unnamed source.

To contact the reporter on this story: Connie Guglielmo in San Francisco at cguglielmo1@bloomberg.net

Last Updated: April 23, 2008 20:03 EDT