Movers Roundup: GMX Resources, Sonic

Among the stock activity stories for Friday, May 8, from AP Financial News:

NEW YORK (AP) — Improving productivity and still-untapped potential from a key natural gas region in Texas should significantly boost GMX Resources Inc.'s earnings, an analyst said, upgrading the stock.

NEW YORK (AP) — Shares of Sonic Corp. dropped after the drive-in restaurant chain said its same-store sales deteriorated in March and April.

NEW YORK (AP) — Shares of Biovail Corp. climbed after a Deutsche Bank analyst upgraded the Canadian drug developer's stock to "Buy," approving of the company's transition to a focus on disorders of the central nervous system.

MILWAUKEE (AP) — Shares of Ralcorp Holdings Inc. rose, a day after the food maker posted better-than-expected second-quarter results that prompted a UBS analyst to raise his estimates, saying the company has hit a "sweet spot."