Motorola Mobility Holdings Inc sold slightly fewer smartphones than expected in the fourth quarter and said it was already feeling pressure from new competition from the Apple Inc iPhone, sending its shares down 6 percent.

In the last full quarter before Motorola's most important customer Verizon Wireless, starts selling the iPhone, Motorola shipments of 4.9 million smartphones were a touch below expectations for 5.2 million smartphones for six analysts contacted by Reuters.

Chief Executive Sanjay Jha said he was already seeing fewer sales of Motorola smartphones after January 11, when Verizon Wireless announced its February launch for a version of the iPhone. AT&T Inc was previously the only U.S. operator.

Since the announcement of iPhone, we've seen a little slowdown, Jha told analysts on a conference call.

He said the lower than expected smartphone sales for the fourth quarter were due to fewer sales of cheaper smartphones rather than its flagship phones.

Including smartphones and tablet computers, a new category for the company, Motorola Mobility expects to sell between 20 million and 23 million units in 2011, Jha said.

The company, which sells television set-top boxes, as well as handsets, said its phone unit would post operating profit margins in the mid-single digit range for 2011, a significant improvement from losses reported in 2010.

Motorola expects to post a first-quarter net loss per share of between 9 cents and 21 cents, but excluding nonoperating unusual items it expects to break even.

The company had already warned its handset profitability would come under pressure this quarter, but Avian Securities analyst Matthew Thornton said the outlook was a bit worse than he expected. He was also disappointed with the company's quarterly profit and its smartphone sales.

The stock has had a good run so people are going to take it out back and beat it up a little unless they say something good on the call about full year guidance, Thornton said.

In its first quarterly report as a separate company, Motorola said on Wednesday it posted a profit of $80 million, or 27 cents per share compared with a loss of $204 million, or 69 cents per share in the year-ago quarter before it became a stand-alone company.

Excluding unusual items, Motorola said its earnings would have been 37 cents per share, slightly ahead of analyst expectations of 36 cents per share, according to Thomson Reuters I/B/E/S.

Smartphones were a little bit light. Earnings quality in the quarter was a little light and the bottom line guidance for the first quarter was a little light, Thornton said.

Revenue rose to $3.4 billion from $2.8 billion in the year ago quarter, in line with the expectations of at least two analysts. About $2.4 billion of its revenue came from the handset business, Motorola said.

Including smartphones and less advanced phones, Motorola shipped 11.3 million phones in the quarter, which compared well with analyst expectations for 10.7 million.

But investors are most anxious about its success with smartphones because the company has revamped itself after years of market share losses to focus mostly on offering smartphones based on Google Inc's Android software.

The company's shares fell to $32.70 in late trading after closing at $34.83 on the New York Stock Exchange. The stock has already risen 5 percent since January 4, the stock's first official trading day on the New York Stock Exchange.

Motorola Inc split in two in January to form Motorola Mobility and Motorola Solutions Inc. Verizon Wireless is a venture of Verizon Communications Inc and Vodafone Group Plc

(Reporting by Sinead Carew; editing by Andre Grenon)