Lenovo swung to a profit on rising demand for its personal computers but missed analysts’ expectations as it spent money to expand its mobile phone business, which it re-acquired last November.

The company made $13 million, or 13 cents per diluted share, an improvement over last year’s loss of $264 million, or $2.98 per share. Analysts polled by Bloomberg expected Lenovo to make $30.7 million.

Healthy demand for Lenovo’s computers in China and India helped boost sales to $4.3 billion, a 55 percent increase over last year’s fourth quarter, when the company’s revenue totaled $2.77 billion.

The re-acquisition of Lenovo’s mobile division appeared to increase the company’s operating expenses, which rose 7.2 percent to $402 billion. Lenovo paid $200 million to buy its mobile division back from a group of investors led by Hony Capital last year after divesting the unit in 2008. The move was intended to increase the company’s presence in China’s burgeoning mobile Internet market.

In its earnings statement, the company said it was “well positioned to participate in the mobile convergence and 3G market growth opportunities in China.” Lenovo launched its 3G, Android-based LePhone in China earlier this month, a move the company called its “first foray into new mobile internet platforms and devices.”

The company’s Chief Operating Officer Rory Read said at the LePhone launch that Lenovo expects 10 percent to 20 percent of its sales will come from mobile Internet services within the next five years, according to reports in the Wall Street Journal.

For the full year 2009, Lenovo made $129 million, or $1.33 per diluted share, on sales of $16.6 billion.