coupon senior bonds. The debentures, due in 2021, will be convertible into XL ordinary shares.

Initial purchasers will have an option to purchase up to an additional $100 million of debentures to cover over-allotments.

A convertible bond is a hybrid security that usually offers current income, which zero coupon bonds do not. Its worth is closely allied with the underlying stock price and it can be converted into company stock.

Goldman Sachs is arranging the sale, according to Reuters, and the bonds are expected to yield 2.125 to 2.625 percent to maturity. They will be convertible to XL common shares at a 28 to 32 percent premium over the shares' Thursday closing price on the New York Stock Exchange of $77.98.