News bites: Groupon shares plunge

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.