Benzinga's Top #PreMarket Losers By: Benzinga via Benzinga December 14, 2015 at 08:22 AM EST Atara Biotherapeutics Inc (NASDAQ: ATRA) shares dipped 37.38 percent to $20.79 after the company reported results from its Phase 2 ... Read More >> Related Stocks: Apple Atara Biotherap Chesapeake Energy DuPont USA Gopro Inc Cl A Newell Rubbermaid