The biggest private equity firm on Wall Street wants to double in size

Steve Schwarzman is the richest CEO in the private equity industry and the firm he founded, the Blackstone Group, manages more money than any of its contemporaries.

But he still sees room to grow, he said in an interview from Blackstone's New York headquarters.

Blackstone has already grown significantly since its 2007 IPO, when it ran less than $80 billion in assets, and now controls more than $300 billion.

That's a four-fold increase in eight years. The growth will slow in the next eight, but Blackstone could still double in size, he said.

"We've communicated to our investors that we have an expectation that we'll be able to grow in the 12%-15% annually without acquisitions," he told Business Insider.

"That would make us, over eight years, roughly double the size. We're always selling things and giving money back. So for us to be double the size it means we've grown quite quickly."

Schwarzman met with Business Insider for a lengthy interview, in which he addressed the best investment he never did, the pro sports team he would like to run (but says he won't buy) and his rule of thumb for making deals.