Benfield Group, the reinsurance broker, is to float in London in the first half of next year.
The company refused to put a figure on the amount likely to be raised in the move, but reports suggested that it could enter the FTSE 250 with an extra £750m in its war chest.
Benfield said the float would give it "additional financial flexibility".
A statement added: "The board believes that it is now an appropriate time to raise further capital by means of a public listing."
Benfield, the world's largest privately owned reinsurance broker, is domiciled in Bermuda, but based in London.
A listing in New York was considered and rejected, because margins would be squeezed by the extra expense of D&O cover in the US and accounting reforms.
Chief executive Grahame Chilton said: "As a group we have taken a serious look at a potential IPO in US markets.
"However, recent high profile events in the US have resulted in an unattractive environment in which to pursue a U.S. IPO at this time."