Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Internet radio king Pandora Media (NYSE: P) were tuning in big gains today, rising as much as 19% in intraday trading after the company reported fiscal first-quarter results.

So what: While investors continue to kick up dust around the debacle that was the Facebook (Nasdaq: FB) IPO, Pandora quietly reported results yesterday that were much better than expected. Revenue for the quarter ended April 30 rose 58% from a year ago, to $80.8 million, easily topping the $74.5 million that Wall Street analysts were looking for. The bottom line was likewise better than expected as the adjusted per-share loss came in at $0.09 versus the $0.18 that analysts had estimated.

Now what: The company's full-year guidance was also music to investors' ears, as the forecasts for revenue between $420 million and $427 million and the loss per share of $0.07 to $0.11 were both better than what analysts were anticipating.

With all of that good news in mind, is it time to hop on board? Some investors may be ready and willing to speculate on the future of digital radio and Pandora, but this Fool isn't quite there. Revenue is growing fast and this quarter's results topped expectations, but the company's GAAP net loss jumped from $6.8 million a year ago to $20.2 million in this quarter as rising costs easily outstripped the jump in sales. There may be a jazzy future ahead for Pandora, but I'm willing to stay off the dance floor until it proves it can make money.

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