The payments from Jupiter's German parent company, Commerzbank, will cover the purchase of the 25 per cent of the company still owned by the employees.
John Duffield, the chairman of Jupiter, and his team of 300 will find out the exact details in the next few days. Mr Duffield is likely to be the biggest beneficiary, standing to net pounds 100m for his 5 per cent stake. Other winners include star fund managers William Littlewood and Edward Bonham-Carter, the brother of actress Helena. The bonuses will be spread across all 300 staff, and even secretaries are expected to get at least pounds 100,000 each.
However Lord Lamont, another Jupiter director, will be spared the wait. As a non-executive, he does not qualify for the scheme.
Mr Duffield is the former husband of Vivien Clore, deputy chairman of the Royal Opera House and daughter of Sir Charles Clore, the founder of the Sears retail chain.
The payouts, which are being calculated at the moment, stem from an agreement hatched in 1995 when Commerzbank paid pounds 169m to acquire 75 per cent of Jupiter. Commerzbank agreed to buy the remaining 25 per cent from Jupiter's staff for a performance-related fee.
Jupiter's profits have since spiralled, topping pounds 117m for the first nine months of this year. Observers believe this strong performance has lifted the value of the employees' stake to at least pounds 500m.
The eye-popping payouts vindicate the decision of Jupiter staff to retain their 25 per cent holding for the last few years. That stake would have been worth just pounds 56m based on Commerzbank's valuation of Jupiter in 1995. Jupiter declined to comment on the size or timing of the payouts.
It is not just the size of its liability that is worrying Commerzbank. Although the German group has attempted to tie in Jupiter's star fund managers until 2002 with a further incentive package, there are fears that once they have been rewarded some will jump ship.