Stocks to Watch: GRPN, MNST, CSTR & More

Check out which companies are making headlines after the bell Monday:

Groupon - The daily-deal website posted earnings of 8 cents a share, topping estimates for 3 cents a share. Meanwhile, the company posted sales of $568 million, missing expectationsfor $573 million. In addition, the firm provided current-quarter revenue guidance that was mostly in line with forecasts. Shares plunged in extended-hours trading. (Click here for after-hours quote.)

Shares of other social-media companies including Facebook and Zynga also fell in after-hours trading.

EBay - The online auction company posted same-store sales that jumped 28 percent in July from a year ago, according to ChannelAdvisor. (Click here for after-hours quote.)

Monster Beverage - The energy-drink maker announced an additional $250 million share repurchase authorization, sending shares higher in extended-hours trading. As of August 13, the total amount available under the authorization is $500 million. Last week, the company reported quarter results that missed expectations. (Click here for after-hours quote.)

Coinstar - The owner of the Redbox movie-rental kiosks announced a planned departure of President and COO Gregg Kaplan in March 2013. Shares were unchanged in extended-hours trading. (Click here for after-hours quote.)

—By CNBC’s JeeYeon Park (Follow JeeYeon on Twitter: @JeeYeonParkCNBC)

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