Bermuda-based insurance company Endurance Specialty has seen some of its initial investors scale back their stake in the company in a sell-off of shares in a secondary offering.

The secondary offering comes a year after the company went public in an IPO on the New York Stock Exchange in February, 2002.

Endurance was one of a wave of re/insurers to set up in late 2001 in response to improving business conditions after a void in capacity following the September 11 terrorist attacks. Founding shareholders, including Aon Corpoartion, Texas Pacific Group and Thomas H. Lee Partners sold off $308 million of Endurance stock in the offering, according to a filing with the US Securities and Exchange Commission (SEC).

The sale reportedly cuts Aon's stake in Endurance to 20.8 percent from 23.6 percent.

In addition to the 8.85 million shares sold off by the founding shareholders, underwriters can also sell 1.33 million more to cover over-allotments.

Investors scaled back their investment in the company a year after the IPO, and three years after they backed the new venture with initial funding of $1.2 billion. The institutional capital was put up in December, 2001.

Endurance reportedly received no proceeds in this offering. Goldman Sachs Group Inc. and Merrill Lynch & Co. jointly managed the secondary offering.

The offering priced at $34.85 per share, a 52 percent increase over the company's IPO pricing of $23 a share, last year.

Endurance shares yesterday closed down seven cents at $35.