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What: Shares of Chinese online game developer Changyou.com (Nasdaq: CYOU) have plunged today by as much as 14% after the company reported fourth-quarter earnings.

So what: Even though the results topped estimates, guidance has spooked investors. Revenue added up to $137.7 million while earnings per share was $1.33. Compare those to the market's expectations of $124.1 million in sales and a $1.09 per share profit.

Now what: Although first-quarter revenue is forecast to be better than expected at $130 million to $134 million, the bottom-line guidance left a little to be desired. Next quarter's profit is forecast to be below the consensus estimate of $1.13 per share, with the company is expecting anywhere from $1.08 to $1.12. Majority owner Sohu.com (Nasdaq: SOHU) also reported today, and both companies' shares are getting slammed today after one-time impairment charges weighed on results.

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