A co-founder of Blackstone's GSO Capital Partners business is going to establish a new family office, but remain at the firm in an advisory capacity.

One of the three founders of a unit at private equity titan Blackstone Group is to leave the credit investment firm to create a family office.

Doug Ostrover will leave Blackstone Group’s GSO Capital Partners unit but remain a senior advisor at US-based Blackstone, it said in a statement last week. Ostrover was one of the founders of GSO.

"The success of GSO as the leading alternative credit platform in the market today is in no small measure the result of Doug's creative thinking and energy," Bennett Goodman and Tripp Smith, the unit's two other founders, said in the statement.

Blackstone bought GSO in 2008. The unit has expanded to oversee $75 billion, making it one of the largest credit alternative investment firms globally.

Before co-founding GSO in 2005, Ostrover was chairman of the leveraged finance group of CSFB.