Blackstone was founded in 1985 as a mergers and acquisitions boutique by Peter G. Peterson and Stephen A. Schwarzman, who had previously worked together at Lehman Brothers, Kuhn, Loeb Inc.. Blackstone has become one of the world's largest private equity investment firms. In 2007, Blackstone completed a $4 billion initial public offering to become one of the first major private equity firms to list shares in its management company on a public exchange. Blackstone is headquartered at 345 Park Avenue in Manhattan, New York City, with eight additional offices in the United States, as well as offices in London, Paris, Düsseldorf, Sydney, Tokyo, Hong Kong, Singapore, Beijing, Shanghai, Madrid, Mumbai, and Dubai.