Stay informed with free updatesSimply sign up to the US banks myFT Digest -- delivered directly to your inbox.The early stages of a long-awaited recovery in investment banking fees is set to boost Wall Street lenders when they report second-quarter earnings starting this week, with mergers and debt deals picking back up after a lacklustre two years. Analysts expect investment banking revenues at JPMorgan Chase, Goldman Sachs, Morgan Stanley, Bank of America and Citigroup will on average rise more than 30 per cent from a year earlier during the second quarter,...