Stocks traded mostly higher at midday on Tuesday, with the major averages building on early gains. The Nasdaq traded above its record high. Shares of Chipotle (CMG) moved higher after it reported same-store sales improved in the fourth quarter, as it continues to recover from a food safety scandal last year. The company also authorized a 100 million share buyback. Canadian firm Gildan Activewear (GIL) has won the auction to acquire the American Apparel brand and some assets. The company paid $88 million in cash for those assets, but it won't be buying any retail stores. Biotech company Sarepta Therapeutics (SRPT) advanced after the company released sales numbers for its new drug to treat a type of muscular dystrophy. The results were higher than analyst expectations.