Such deals are attractive to insurers as it helps them manage risk. These insurance blocks have become popular targets for private equity buyers including Apollo Global Management Inc., which set up Athene Holding Ltd., and KKR & Co. as they seek to eke out returns in a low interest-rate environment. American International Group Inc. agreed in July to sell a stake in its life-insurance and retirement-services business to Blackstone, which will also manage some of the unit’s assets. U.S. insurer Prudential Financial Inc. said last week it would sell an annuities subsidiary for $1.5 billion to Carlyle-backed Fortitude Group Holdings LLC.