owen analyst Oliver Chen has a message for brick-and-mortar retailers: Be afraid of the Amazon Prime. Be very, very afraid. According to Cowen’s own data, Amazon.com’s ( AMZN ) annual membership program is expanding its footprint. And the most exposed to the phenomena are broad line retailers like Target ( TGT ) and Wal-Mart Stores ( WMT ), department stores like Kohl’s ( KSS ), JC Penney ( JCP ) and Macy’s ( M ) and warehouse clubs like CostCo ( COST ).