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 Pandora Media Inc. (NYSE:P) jumped more than 14% Monday after the Internet radio specialist both released December audience metrics and announced a new automotive advertising campaign.

So what: First, Pandora says active listeners and listener hours for December each rose 13% year-over-year to a record 76.2 million and 1.58 billion, respectively. This, in turn, translated to an 8.6% listening market share for Pandora in U.S. radio, up from 7.58% at the same point last year.

What's more, Pandora announced it will begin rolling out in-car advertising solutions later this month, with several big names already on board, including BP, Ford, State Farm, and Yum! Brands' Taco Bell.

And why not? Pandora is already available in nine of the country's 10 best-selling passenger vehicles, and more than 4 million users have activated the service through their vehicles' native integration so far -- a 244% increase over the past year.

Now what: The renewed growth of Pandora's user base is encouraging, especially considering it indicates the worrisome launch of Apple's iTunes Radio last September may not bear as much a negative impact as skeptics had originally feared. And remember, despite growing listener hours by only 17% year over year in the most recent quarter, Pandora has done a great job growing its top line, which rose 50% over the same period to $181.6 million.

Adding new automobile ads into the mix should serve as a solid complement to those efforts, and could provide just the push Pandora needs to finally achieve sustained long-term profitability. When that happens, patient Pandora shareholders should be rewarded handsomely.