The fallout from America’s mortgage crisis looked very close to going right to the very top last night — to claim the scalp of the head of the world’s biggest bank.

Chuck Prince’s resignation as chairman and chief executive of Citigroup, while unconfirmed as The Times went to press, appeared a near-certainty last night as the group convened an emergency meeting for the weekend and failed to deny rampant rumours of their head’s imminent departure.

The departure of Mr Prince in the wake of a $6.5 billion (£3.1 billion) third-quarter writedown, mostly relating to the credit crunch, is only the latest in a series of oustings as first senior executives, and now the big bosses, began to fall like dominos.

First, Warren Spector left his position as Bear Stearns’s co-president as two hedge funds run by the Wall Street firm collapsed over the summer after plunging headlong into bonds backed by high-risk sub-prime mortgages. These promptly plummeted in value after a surge in defaults on the underlying home loan assets.

Then came Peter Wuffli, who left his position as chief executive of UBS, after the bank closed its Dillion Read Capital Management hedge fund. He was followed by Huw Jenkins, who resigned as chairman and chief executive of the UBS investment banking division after it took a SwFr4 billion (£1.65 billion) writedown on its hedge fund and mortgage-backed securities businesses.

But the biggest resignation to date had been Stan O’Neal, who stepped down as head of Merrill Lynch this week after taking the heartening, but unusual, step of accepting responsibility last week for an $8.4 billion third-quarter writedown that left it with a $2.2 billion loss – the biggest quarterly deficit in its 93-year history.

Of course, these are only the biggest casualties. There have been plenty of other, slightly lower level departures, such as David Martin and James Stehli, respectively global head of interest rate products and head of collateralised debt obligations at UBS. Or Thomas Maheras, the head of Citigroup’s fixed-income division.

But these redundancies, too, pale into insignificance against the vast job cuts that have been administered across the financial services industry as a consequence of the housing slump, the decline in mortgage-related investment valuations and the credit crunch. In the first nine months of the year alone, about 130,000 jobs were lost in the US financial services industry, many of them related to the mortgage meltdown. This catapulted the financial sector ahead of carmaking to become America’s biggest source of redundancies.

Unfortunately, we are likely to see an acceleration in redundancies over the next few months as conditions continue to worsen. In the past few days – just when we thought the worst of the credit crunch was over – analysts have been forecasting massive additional writedowns relating to sub-prime mortgage-related investments and buyout loans. Citigroup is expected to write down another $5 billion this quarter, on top of the $8.4 million charge it took in the previous three months. Merrill Lynch is estimated to be sitting on a further $10 billion of losses, on top of the $8.4 billion it just took. UBS is said to be preparing an additional $8 billion write-off, on top of the one it has just made.

These writedowns will no doubt be followed by others and the list of casualties, at all levels, will expand.

Guessing whose head will be the next to roll has long been a popular game on Wall Street, but it is being played more vigorously now than at any time in years.

The name that perhaps comes up the most — at least after Mr Prince — is Jimmy Cayne, the chief executive of Bear Stearns. Mr Cayne has been away from the office because of ill-health and, with expectations of a fourth-quarter writedown still to come, there has been much speculation that it is time for the 73-year-old to retire.

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