• by Mark Walsh  @markfwal, February 5, 2014

Online radio service Pandora on Thursday reported a 52% gain in revenue in the quarter ending December 31, with mobile advertising again helping to boost sales.

The company had earnings of four cents a share on revenue of $200 million. Excluding certain expenses, Pandora would have earned 11 cents a share. Wall Street analysts surveyed by FactSet were expecting Pandora to earn eight cents a share on sales of $199.8 million.

Advertising revenue increased 39% to $162 million from a year ago in the quarter, while subscription sales continued to grow at a faster clip, growing 132% to $38.8 million.

Analysts expected mobile advertising to again make up the majority of Pandora’s ad revenue, after breaking $100 million for the first time in a quarter in the third quarter.

In terms of usage, total U.S. listener hours climbed 16% to 4.54 billion hours in the fourth quarter from 3.91 billion a year ago. Pandora's share of total U.S. radio listening in October surpassed 8%, while it still draws less than 1.5% of the radio industry’s $15 billion in local ad sales. The vast majority of listening on Pandora now takes place on mobile devices rather than PCs.

For the current quarter, Pandora projects it will lose between 14 cents and 16 cents a share on revenue ranging from $170 million to $176 million. Analysts had forecast a loss of 12 cents a share on sales of $173.6 million. 

Even so, Pandora CEO Brian McAndrews said the company plans to continue to “aggressively invest” this year to maintain audience and engagement growth. “Our bias will continue to be toward revenue growth and capturing additional market share." 

Because of the lower-than-expected guidance, Pandora’s shares were down about 9% in after-hours trading after closing Thursday at $35.83.