Updated from 8:57 a.m. ESTShares in Jack in the Box ( JBX) Thursday, well, popped. The company jacked second-quarter earnings guidance to 42 cents to 44 cents a share. The San Diego-based fast food chain had previously forecast EPS of 28 cents a share, vs. 44 cents a share a year ago. The consensus estimate is 28 cents a share, according to Thomson One Analytics. Same-store sales are expected to grow a revised 7.5%, compared with a previous forecast of 4% to 4.5%. The company attributed the improvement to lower food costs, new products, labor cost controls and improved leverage. Shares rose $2.33, or 9.3%, to $27.30, a new 52-week high.