Among the stock activity stories for Friday, July 20, from AP Business News:
— Shares of Chipotle Mexican Grill plunged more than 21 percent after the restaurant chain's second-quarter sales and fears of rising food costs led to analyst downgrades on Wall Street.
— Advanced Micro Devices Inc.'s shares plunged to their lowest level in more than three years after the chipmaker reported that economic weakness dragged down its second-quarter results and would hurt its performance through the summer.
