Jim Armitage: Should Jamie Dimon really still be head of this scandal-ridden bank?

Outlook Another day, another $100m fine for JP Morgan, the Wall Street banking giant that has deftly donned the pantomime villain costume of the investment banking world.This time, it's the payout for the screw-ups and cover-ups around the London Whale trading scandal, which saw a small team of badly managed bankers run up losses of $6bn.

The bank is in the thick of the biggest blizzard of fines, investigations and court cases to face any bank. With allegations from mortgage securities fraud to shoddy credit card billings to Libor fixing: everywhere you look for scandal, JPMorgan seems to be there.

Its troubles are the biggest topic of chat in the bars and restaurants of the City and Wall Street, and little wonder. Is its litany of debacles and scandals merely a by-product of being the biggest bank in the world? The chief executive Jamie Dimon would like you to think so. Last year he was grumbling that one of the big inquiries was into events that took place at Bear Stearns and Washington Mutual before JPMorgan even owned them.

But there are plenty of home-grown JPMorgan scandals that Mr Dimon can't duck. The Whale fiasco was smack bang in his area of expertise, and happened because of disastrously poor oversight. Libor rigging, if allegations against JPMorgan are proven, is a function of a corrupted corporate culture: and that comes from the top.

So here's the billion-dollar question: should Mr Dimon still be at the top of the organisation, where he sits as combined chairman and chief executive?

More precisely, would half of these scandals have happened if it was Bill Winters, not Jamie Dimon at the top? Mr Winters, an Anglophile American based in London as JPMorgan's co-chief executive of investment banking, was tipped as a possible successor to Mr Dimon, but the boss fired him in 2009.

He was one of the few very senior investment bankers back then who "got" the public anger. Shortly before his ousting, he admitted some of his peers in the industry had been "greedy" and "inept" – a sentiment that many bankers themselves agree with.

A popular leader among his thousands of London colleagues, Mr Winters had a reputation for taking pains to understand the risks his bankers took. Some reports have even suggested that he expressed concerns about the London Whale's department before he left, arguing they should be making more disclosures about the risks they were taking.

Even if Mr Winters had not been running the entire bank in recent years, Mr Dimon could clearly have done with his experience, including a quarter of a century at the firm. It was a major mistake to lose such a wise lieutenant. But wealthy Wall Street bosses have a track record of failing to manage the egos of the extremely wealthy, ambitious and egotistical colleagues at the top.

Before axing his lieutenant, Mr Dimon should have taken note of the events a decade ago at Citigroup. There, Sandy Weill, who built the bank into the world's biggest financial services business, ousted his most talented executive, allegedly fearing the extent of his ambitions. Mr Weill eventually resigned as his once-great bank fell into a mire of regulatory inquiries and litigation. That banker's name? Jamie Dimon.