American banks are using some of their vast capital to better remunerate shareholders.It's been an eventful summer for companies on the stock exchange, so even an active investor could be forgiven for missing a major event in the financial sector -- this year's version of the annual U.S. bank stress tests. For those who might be unfamiliar, these are a series of theoretical exercises aimed at judging whether a bank would be able to withstand severely adverse economic conditions. The tests are conducted by t ...