About
Willett Advisors is a single-family office established in 2010 to manage the personal and philanthropic assets of Michael R. Bloomberg, founder of Bloomberg L.P. and former Mayor of New York City. The firm is headquartered at 650 Madison Avenue in Manhattan and operates under the leadership of Steven Rattner, who serves as Chairman and Chief Executive Officer. Willett's investment objective is to achieve long-term capital appreciation through construction of a diversified portfolio spanning multiple asset classes. The firm employs a flexible investment approach, deploying capital both through direct investments and carefully selected third-party managers. Willett's investment mandate encompasses public markets, private equity and credit, hedge funds, real assets, and direct venture investments. As of early 2026, the firm has made 16 total investments with an average round size of approximately $149 million, demonstrating a focus on growth-stage and later-stage opportunities. The portfolio includes Series B investments (7 total, averaging $81 million per round), Series C investments (3 total, averaging $187 million per round), and Series A investments (2 total, averaging $112 million per round). Notable portfolio companies include Circle and Finch Therapeutics, with the portfolio containing 13 active companies and one unicorn-status investment. Willett has generated four portfolio exits to date. Beyond venture and growth equity, the firm manages Bloomberg Philanthropies' assets, integrating investment returns with philanthropic mission across education, public health, environment, and other focus areas. The organization maintains a lean team structure typical of family offices, with verified leadership including Brian Allen as Managing Director of Private Equity. Willett operates with no external limited partners, investing solely the Bloomberg family's capital and philanthropic endowments.