John Mack, president of Morgan Stanley Dean Witter, declared recently that those who had left would not be re-admitted. 'You have to be very careful about what it does to morale,' he said. A spokesperson for another leading bank confessed: 'We've been very happy to see the back of some of the people that have left, .'
But others are more forgiving. A spokesperson for Goldman Sachs in London said that for high performing employees, the door would be 'left ajar'. Phyllis Rock, a senior director of human resources at Merrill Lynch for Europe, Middle East and Africa, also offers consolation to any wavering ex-Merrill employees.
Staff may want to come back when it does not work out, she says, and the bank would not close the door to high-performing, exceptional staff.
But 'not working out', is no guarantee that bankers will return. According to Gawn Rowan Hamilton, former corporate financier at Schroders and now chief financial officer at mergermarket.com, leaving the bank is such a big decision that the people who jump are very unlikely ever to go back. Many of them are trying to get out of the banking environment itself, he says.
This is confirmed by John St John, a former head of global capital markets at Lehman Brothers. He says that when you leave an investment bank, you leave a very substantial earning stream, and if you do that, then you do so for a very good reason.
Julie Meyer, chief marketing officer of the internet networking group First Tuesday, is accustomed to seeing financiers with their own business plans at the group's meetings.
'Many people who work in the investment banks are frustrated by the entrepreneurs who come to them and look to make a killing if all goes well,' she says. 'If you are going to work 100 hours a week, why not work for yourself? It comes down to getting comfortable with a high level of risk and wanting to work to ensure your own future, not to make the more senior partners in the firm even better-off.'
However, a large upside is not the only appeal of start-ups. A recent survey by recruiters Norman Broadbent found that a quarter of executives in hi-tech firms expected to make personal gains of 20m (󌍑m). But it also found that the opportunity to shape a company was almost as appealing as an IPO.
Charles Murphy, former managing director of European financial services at Morgan Stanley, now chief executive of venture capital firm the Ant Factory, which specialises in funding new economy start-ups, says that in a smaller company it is the opportunity to get involved in strategic decision-making that is important. Serena Doshi, chief executive of the youth site Liv4Now.com and one-time corporate financier at Schroders, confides that rather than advising on media strategies, she was keen to implement them herself.
But the world beyond the bank can also be unsettling. Hamilton, at mergermarket.com, says: 'The real world is not the same as investment banking, where advisers work all hours. While I'm working as hard as I ever did, spending time on the outside makes you realise that most people keep more conventional hours. Not everyone works 12-hour days it's only investment bankers.'
Nicholas Hall, founder of Silicon Valley-based website startupfailures.com, says working in a start-up is the business person's equivalent of being a Hollywood star. But far from offering the existence of a film star, entrepreneurialism can also be unsettlingly mundane. He warns: 'Some people find that being an entrepreneur is not for them. It implies a certain lifestyle in which you have to do certain things that you wouldn't have to do in a bank. Don't be surprised if you end up licking stamps, making your own photocopies and installing your own telephone systems.'
The headhunters who persuade investment banking staff to move to technology firms do not dwell on these practical aspects. Instead, moving to the new economy is presented as an emotional calling.
'I point out that you should be following your heart and passion,' says one leading headhunter, 'and that seems quite effective.'
The wisdom of following your heart is only now being tested. According to Hamilton, the majority of investment bankers in start-ups are still on their honeymoon period. The strength of recent marriages will be tested in the coming months.
Lucy Rice, First Tuesday's chief financial officer and former accountant at the Silicon Valley branch of PricewaterhouseCoopers, thinks that these marriages are stronger than they may seem. 'The entrepreneurial spirit of Silicon Valley is coming to Europe and it is more than just a passing phase,' she says.
Nadim Nsouili, formerly of Morgan Stanley, and now head of Lago Ventures - a fund he set up to invest in early stage technology and telecoms companies - also believes that many of the new entrepreneurs will weather the current storms. Having left Morgan Stanley in March, after just one year in its telecoms group, he says he is planning for a five- to 10-year time horizon in his new venture.
Where marriages do hit the rocks and former bankers don't want to go back to the bank, Nicholas Hall's website is always available.
In some cases other failed entrepreneurs may prove more sympathetic than investment banks.