Hundreds of office workers in south Wales are to receive an average windfall of around £37,000.
The Admiral group is expected to be valued at up to £776m
Their employer, insurance firm Admiral, is selling off a stake worth about 10% of its value.
Around 1,400 staff in Cardiff and Swansea, who are members of the company's share-ownership scheme, are expected to qualify for the payouts.
This is good news for Michelle Davies and Rhys Evans who are about to exchange their vows.
The admiral employees have worked for the car insurer for 10 years and are getting married at Christmas.
Together they hope they will qualify for a payout of around £75,000 under the company share-ownership scheme.
"This will make thing a lot easier," said Ms Davies. "We wouldn't have to borrow money."
They intend to upgrade their arrangements and will be flying first class to Canada on their honeymoon.
"Also I'll be looking for a ring with diamonds - it's made a big difference."
Admiral, part-owned by its 1,500 workers, has set a price of 275p a share for its stock market flotation.
Michelle Davies and Rhys Evans want fireworks at their wedding
In conditional trading ahead of the firm's full market debut on Tuesday, Admiral shares rose 3.75% to 285.5p.
Individual windfalls depend on length of service with some staff set to make hundreds of thousands of pounds.
Admiral will have a market valuation of £711m(1.04bn euros) when it floats next week.
The amount paid out to its employees will depend on each person's role and length of service.
Senior managers will get the most, but even the most junior workers will own shares valued at £10,000.
The company has around 1,100 staff in Cardiff and another 400 in Swansea.
Admiral announced that it was seeking a stock market listing in April after rapid growth at its online business elephant.co.uk and higher premiums at Diamond, its insurer targeted at female drivers.
The decision to float comes five years after Admiral was sold to its management team in a buy-out backed by Barclays Private Equity.
Launched in 1993, the Cardiff-based group now has more than 900,000 customers across its four brands.
Admiral's chief executive, Henry Engelhardt, said the global offer had generated
a strong response from institutional investors.
"I'm absolutely thrilled with the outcome," he said.
Chairman Alastair Lyons added: "We look forward to continuing to create value
for all our shareholders as we pursue our successful focused business