Wellington is planning to raise £120m on the stock market to increase its grip on subsidiary, Wellington Re.
Up to £76.1m of the proceeds from a share placingwill be ploughed into the holding company, Exali Re.
The placing and open offer prices the shares at 58p, a 9.4% discount to the mid-market market price of 64p on 8 October, the day before the announcement.
The Wellington group will place 62 million shares with pre-arranged purchasers and offer another 144 million on a 20 for 39 basis to existing shareholders.
Swiss Re, which owns about 9.5% of Wellington, has agreed to take up nearly 6 million of the shares in the placing. It will take up its full entitlement under the open offer - a total of 19.6 million shares worth £11.4m. The fund-raising comes after Wellington raised £70.4m in August when it sold 149 million shares at 50p each.