Facebook Inc., operator of the world’s largest social network, climbed the most since its first trading day after researcher ComScore Inc. suggested that marketers can use the site effectively to spur purchases.

Shares of Menlo Park, California-based Facebook rose 4.4 percent to $27.46 at 11:45 a.m. in New York, and earlier touched $27.76 for the biggest intraday gain since shares began trading on May 18. Facebook had declined 31 percent since its initial public offering.