Och-Ziff Capital Management, one of the world’s biggest hedge fund groups, on Monday brushed aside concerns about the tax status and valuations of alternative asset managers by filing for an initial public offering that could value it at as much $20bn.

The 18 partners in Och-Ziff, which has $26.8bn in assets, will sell part of their holdings and reinvest all the proceeds in the company’s funds. They will not be able to withdraw the money for five years.