Markets are jittery at the start of an eventful week that will see the U.S. second-quarter earnings season kick off, the release of inflation data in several countries, and testimony by Federal Reserve Chair Jerome Powell which will be scrutinised for any talk of tapering. The next question is whether company earnings will support Wall Street's run higher. JPMorgan JPM.N, Goldman Sachs GS.N, Bank of America BAC.N and other big banks kick off results from Tuesday .