Australia's Macquarie Bank, which has been on an acquisition spree in the United States for the past three years, has acquired a small investment banking boutique founded by former New York City mayor and presidential hopeful Rudolph Giuliani.

Macquarie bought Giuliani Capital Advisors, which has 100 staff and offices in Chicago, New York, Los Angeles, Atlanta and Troy, Michigan. Macquarie currently has 350 people in its investment banking department.