News bites: Groupon shares plunge

Groupon lost a quarter of its market value after the company revealed that it had to take a smaller cut of revenue on its daily deals, Reuters reports.

Pandora is capping free mobile listening due to soaring royalty costs, Bloomberg explains. 

Apple CEO Tim Cook is urging investors to be patient, according to The Wall Street Journal. 

I.B.M. is exploring new uses for its Watson supercomputer, The New York Times writes.

Apple, Google, Facebook and hundreds of other companies signed a brief urging the Supreme Court to legalize same-sex marriage, Wired reports. 

---