Apollo Global Management Inc said on Monday it will merge with Athene Holding Ltd in an $11 billion all-stock deal, bringing in-house an annuities provider that helped turn it into one of the world’s largest corporate credit investors. Apollo has been getting paid lucrative fees by Athene, in which it controls a 35 percent stake, for more than a decade, providing asset allocation services and directly managing a portion of Athene’s assets across its investment platform, primarily in its ever-expanding credit business. Yet Athene’s shares underperformed the insurance sector following its stock market debut in 2016, prompting a bid from Apollo for its assets. Apollo estimated the tax-free combination could result in its earnings more than doubling from 2020. Its existing stake in Athene did not contribute to earnings under accounting rules, despite representing 40 percent of Apollo’s assets under management and 30 percent of its fee-related income. A merger …