Michael Larson is one of the most powerful men in US wealth management you have never heard of. He is the chief investment officer for Bill and Melinda Gates Investments (BMGI), and as such is in charge of managing Bill’s personal wealth through Cascade Investment, as well as handling the Bill & Melinda Gates Foundation Trust endowment. Despite his high-profile job, he works hard and successfully to stay out of the public eye — Cascade declined to speak for the purposes of this article.

Bill Gates hired Larson 22 years ago to take over the investment of his personal wealth, which was about $5bn at the time. Since then Gates’s fortune has grown to around $80bn (of which he has given away around half) after Larson diversified the funds out of Microsoft, Gates’s software company, and into a broad range of investments.

Cascade is not a family office in the traditional sense and does not like to call itself one. It does not handle logistics, payroll or expenses for the foundation and is purely an asset management firm that invests Gates’s personal wealth. BMGI is an organisation that manages the portfolios of Cascade, the Bill & Melinda Gates Foundation Trust and other entities, but again it does not label itself as a family office.