I learnt about the gun a few days ago as I poked around the history section of the JPMorgan Chase website. Among the company’s various possessions, it revealed, was the weapon that had been used by one of its own to murder a rival who dared to get in his way.

The deed was done long ago – on July 11 1804, to be precise – in a galaxy far, far away, which is to say Weehawken, New Jersey, and more than eight decades have passed since the pistol that fired the fatal shot was acquired by one of JPMorgan’s predecessor banks.

But despite the passage of time, that firearm struck me as strangely relevant to today’s Wall Street. There is no bigger story in financial circles at the moment than the travails of Jamie Dimon, JPMorgan’s chief executive, and I think the weapon in his bank’s hands is a symbol of one of Mr Dimon’s biggest underlying problems: the vast wellsprings of weirdness that sit beneath some of our more august financial institutions.