Facebook stock jumped to record highs Thursday as strong earnings from the leading social network sparked fresh buying. Facebook said Wednesday profits leapt to $791 million during the three months ended June 30 in a 138 percent increase from a year earlier. Revenue in the quarter surged to $2.91 billion, with approximately 62 percent of that money coming from ads served up on mobile devices such as smartphones or tablet computers. The number of people who visited the online social network at least once a month climbed to 1.32 billion in a 14 percent rise from the same quarter last year, according to Facebook.