Private equity firm Apollo Global Management said on Monday it had agreed to buy Athene Holding in an all-stock deal valuing the retirement services company at about $11 billion.

Under the terms of the deal, each outstanding class A common share of Athene will be exchanged for 1.149 shares of Apollo common stock.

Existing Apollo shareholders will own about 76% of the combined company, and Athene investors will own the rest.

The deal will create a company with a pro-forma market value of $29 billion, providing products and services in the investment and retirement income space.