Apollo Global Management LLC, the private equity firm run by Leon Black, received approval from investors to increase the limit on its next buyout fund to $17.5 billion, which would make it the largest buyout fund since the financial crisis of 2008, Bloomberg reported. Citing two unnamed sources familiar with the deal, Bloomberg said the New York-based firm increased the maximum from $15 billion, following expressions of interest from investors in putting in as much as $20 billion. At $17.5 billion, Apollo's fund would be 19 percent larger than its prior funding vehicle, a $14.7 billion pool raised in 2008. An Apollo affiliate, AP Alternative Assets LP, provided financial backing for Athene Holding Ltd.'s $1.55 billion acquisition of Aviva USA last year.