Why Marvell Technology Group Ltd. (MRVL), Petroleo Brasileiro Petrobras SA (PBR) and Mattress Firm Holding Corp. (MFRM) Are 3 of Today’s Worst Stocks By: InvestorPlace September 11, 2015 at 12:42 PM EDT Read More >> Related Stocks: Continental Resources Goldman Sachs Group Marvell Technology Inc Petrobras - Petroleo Brasileiro S.A. Plains All American Pipeline LP