Welcome to the new Golden Age on Wall Street. JPMorganChase, our biggest bank by nearly every measure, is pumping out $40 billion in profits a year, and its formidable chairman and C.E.O., Jamie Dimon, told me recently that he sees no end in sight to the machine’s ability to generate the majority of those profits. In its recently announced third-quarter, the bank made a profit of $11.7 billion, which includes a $2.1 billion reversal of Covid-related loss reserves that the bank believes are no longer applicable. The bank also has another $20 billion of accrued reserves on its balance sheet that could be reversed and brought back into earnings if the economy continues humming.