Rare is the financial transaction in which all sides can be declared a winner. Not so with a complex transaction in the insurance industry recently, after which all three companies involved enjoyed a share price spike. That deal — between retirement specialist Voya Financial, the private equity group Apollo Global, and the insurance roll-up Athene Holding — was a genuine win/win/win, and it explains why asset managers with their roots in private equity or hedge funds are pinning their futures on insurance.