InfoSpace ( INSP) soared 21% after posting a stronger-than-expected third quarter and guiding toward unexpected fourth-quarter gains. The Bellevue, Wash., Internet media firm made $11.3 million, or 32 cents a share, down from the year-ago $13.4 million, or 37 cents a share. Revenue rose to $83 million from $67 million a year earlier. Analysts surveyed by Thomson First Call had forecast a third-quarter profit of 18 cents a share on sales of $77 million. InfoSpace said mobile revenue surged 55% from a year ago to $39 million, driven by growth in its media download business. "We are pleased with our third quarter results," said CEO David Rostov. "We continue to execute against initiatives that enhance our position in mobile and leverage our unique combination of search and mobile assets." InfoSpace also guided to a fourth-quarter profit of 25-28 cents a share on revenue of $85 million. Analysts were looking for a 15-cent profit on sales of $86 million. Late Tuesday, shares of InfoSpace rose $4.77 to $27.