JPMorgan Chase yesterday told a tale of two banks. It provided an interesting prism through which to view the post-crisis debate about whether large banks should be torn asunder in a Glass-Steagall-style separation of investment and commercial banking. Net revenues at JPMorgan split pretty evenly between the two. Its investment bank followed Goldman Sachs' record second quarter, with fees of $2.2bn driving a near-quadrupling in net income. It is to cease breaking out its mortgage-related and leveraged lending exposure, closing a chapter in the credit crunch story.

Crunch time, however, persists in the retail business, with expected losses increasing for prime and subprime mortgages as well as for credit cards. True, early-stage delinquencies are moderating, but it is anyone's guess whether that is the spring of hope or only a rare bright day in a winter of despair.

Leaving aside unusually high earnings in JPMorgan's investment securities portfolio, a corporate bucket that straddles the dividing line, “bog-standard” banking (commercial and retail banking, plus cards) made a loss of about $290m, versus $2.2bn of income in “high octane” investment banking, asset management and treasury and securities services. Costs relating to troubled loans in the investment bank doubled year on year, with a sharp jump quarter on quarter in the loss rate. But bog-standard banking dwarfed its high-octane counterpart, accounting for more than 90 per cent of the group's $9.7bn in credit costs.