HSBC Upgrades Petrobras, But Warns Of 'Challenging Execution' By: Benzinga via Benzinga June 30, 2015 at 07:42 AM EDT In a report published Tuesday, HSBC analyst Luiz Carvalho upgraded the rating on Petroleo Brasileiro Petrobras SA (ADR) (NYSE: PBR) from ... Read More >> Related Stocks: HSBC Holdings Plc ADR Petrobras - Petroleo Brasileiro S.A.