Shares of Pandora Media Inc. tumbled in extended trading Tuesday after after the Internet radio company said its full-year loss will be wider than previously forecast, and sales will be below plan as well.

The loss for the year will be 9 cents to 12 cents a share, the Oakland, California-based company said in a statement. Pandora in August predicted a loss of 4 cents to 8 cents. The company also lowered its sales forecast to $422 million to $425 million from as much as $432 million.

Pandora fell 17 percent to $7.80 in extended trading. The stock rose 5.7 percent to $9.47 at the close in New York and had declined 22 percent since a Sept. 6 report by the Wall Street Journal that Apple Inc. plans to offer a competing service.