Shares of RealNetworks (NASDAQ: RNWK) plummeted Thursday, following disappointing 2007 guidance announced with its fourth quarter earnings .

The firm dropped 14.53 percent, or $1.55 to $9.12 in afternoon trading on the Nasdaq Stock Market.

Revenue at the Seattle-based provider of online music and gaming services grew 50 percent in the fourth quarter, beating Wall Street expectations. However the company projected revenue in the range of $540 million to $560 million for 2007, below Wall Street's current projection of $572.6 million.

ThinkEquity’s Darren Aftahi this morning cut his rating on the stock to Accumulate from Buy, as disappointing 2007 guidance masked solid 4Q results.

We continue to like the asset base Real is building in order to capitalize on media convergence, he told clients in a note on Thursday, however, we also are looking for revenue growth acceleration from the company.