NEW YORK (Bloomberg) ? Axis Capital Holdings Ltd. investors including Marsh & McLennan Cos. sold $558 million of shares in the Bermuda-based insurer on Friday.

They were the latest group of original investors in post-September 11 Bermuda insurance start-ups to capitalise on the companies? success.

The investors sold 20 million shares at $27.91 each, even with the stock?s closing price of $27.91on Friday. Morgan Stanley and Citigroup Inc. managed the sale and shared fees of as much as $18.2 million.

Marsh & McLennan, the largest insurance brokerage, J.P. Morgan Chase & Co., Blackstone Group LP and other investors created Axis after the September 11 terrorist attacks, which caused a jump in insurance rates. The company sold $473 million worth of shares in an initial offering last year.

Marsh and J.P. Morgan were also instrumental in setting up Bermuda-based ACE Ltd. and XL Capital in the 1990s and Mid-Ocean Re ? later bought by XL ? in the mid-1990s.

Other companies whose founding shareholders have either sold parts of their original investments or intend to include Arch Capital Group Ltd., Montpelier Re and Endurance Speciality.

ACE Ltd.?s spin-off of subsidiary ACE Guaranty (AGC) is set to take place this week, according to the Associated press.

The bond insurer, which has been renamed Assured Guaranty Ltd., is expected to raise up to $980 million.

ACE first announced its plans to sell off most of its financial guaranty business in December, saying it would likely go public on the New York Stock Exchange in the first half of 2004.

The decision to do the IPO was said to free up funds to expand its core business as a property and casualty insurer.

ACE in a regulatory filing that it plans to sell 49 million shares of the company at an estimated price of $18 to $20 per share. When ACE initially announced in December that it would spin off this part of its business through an IPO, it said it could shed up to 75 percent ownership but the latest filing said the company could retain 35 percent.

However, it was reported that ACE?s stake in Assured Guaranty could still drop to 25 percent if the group of 10 underwriters - led by Bank of America Securities LLC, Goldman Sachs & Co. and Citigroup - buy 7.35 million more shares from ACE in case there is heavy interest from investors.

Last year, AGC posted gross premiums of $349.2 million and total revenue of $512.3 million, the offering document shows. That compared with $417.2 million in gross premiums and revenues of $302 million in 2002.