Security has been stepped up at 270 Park Avenue, global headquarters of JPMorgan Chase, ahead of the 10th anniversary of the September 11 attacks. At a cordon, metres from the entrance, one of a rank of security guards asks for the name of the appointment. “Mr Dimon!” he beams and extends his hand to shake rather than frisk. “Oh, sir, we are all friends here. We’re family!” Upstairs, his relative, Jamie Dimon, the chief executive, is trying to see past the post-crisis upheaval of the banking industry and the gloomy macroeconomic picture that has produced a summer of discontent in world equity markets.