The company's stock plunged $1.69, or 18 percent, to $7.76 in after-hours trading after the quarterly results were released.
Despite the weak outlook, Pandora continues to gain in popularity. The company said listener hours in November rose 58 percent from a year ago to 1.27 billion, while the number of active listeners grew 45 percent to 62.4 million. Its share of radio listening hours in the U.S. rose to 7.09 percent from 4.32 percent a year ago.
The company has been pressing federal lawmakers to pass a bill that would reduce the royalties it pays to performers and recording companies.
Kennedy said Tuesday that royalties were "extraordinarily, unfairly high by any measure." He said Pandora pays more royalties than any other radio company in the U.S. and more than the total paid by all the radio companies in any one country outside the U.S.