Pandora, the web radio company that recommends music to its more than 80 million registered users, has filed an S-1 form with the Securities and Exchange Commission, the first step in the process of going public. In its filing, the Oakland-based company said it plans to raise up to $100 million.

Pandora's filings indicate that it grossed $55.2 million in the fiscal year that ended in January. Pandora also turned a profit in the fourth quarter. In 2010, the company narrowed its annualized losses to $16.8 million, down from a loss of $28.2 million in 2009. (Last year, Pandora ranked No. 253 on the Inc. 5000 list, with a three-year growth rate of 1,221 percent.)

The company, which was founded 11 years ago, has seen its share of ups and downs. Four years ago, red tape nearly killed the company. A federal ruling more than doubled royalty payments for Web radio stations. "Our investors wanted to shut us down," Pandora founder Tim Westergren told Inc. in late 2008. "We were just hemorrhaging money."

To save the company, Westergren sent a mass e-mail to customers asking them to write members of Congress to demand that the ruling be reviewed. Nearly 2 million Pandora users followed suit, and the ruling was amended.

Besides government interference, the online music business is always changing and not for the faint of heart. As the company notes in the "risks" section of its S-1: "Internet radio is an emerging market, and if we are unable to increase the number of listeners and listener hours or to convince advertisers of the benefits of our advertising products, our business and future prospects will be harmed."

In a nod perhaps to forefathers in the online music space, Pandora's lawyers also noted that "[t]hose who own copyrights in musical works are vigilant in protecting their rights and the licensing structure that we operate under may change or cease to exist, either of which could result in a material increase in our content acquisition expenses."

Pandora's IPO news comes on the heels of Demand Media's recent IPO; the social networking site LinkedIn and the bakery chain Crumbs have also recently filed to go public.