The stock was down 14% at $12.27. During the regular trading session the shares fell 39 cents, or 2.7%, to $14.27.
In the fourth quarter, Pandora posted a net loss of $8.18 million, or 5 cents a share, the company said in a statement. A year ago Pandora lost $3.91 million, or 31 cents a share.
Excluding one-time items, Pandora lost 3 cents a share. Analysts had predicted a loss of 2 cents a share.
Fourth quarter revenue was $81.3 million, a 71% increase from a year earlier but lower than the $83 million in revenue forecasted by Wall Street.
Advertising revenue came in at $72.1 million, a 74% year-over-year increase, the company said.
Pandora went public in June, selling 14.7 million shares of its stock at an initial public offering price of $16. After an early initial bump on high demand, the stock has fallen below its IPO price.