Bill Gates is the second richest man in the world (after Amazon's Jeff Bezos), with a net worth of over just under $95 billion as of August 17, 2018, according to Forbes. He dropped out of Harvard University and turned into a technology entrepreneur founding Microsoft (MSFT) in 1975. Over decades, Gates successfully built it into a major technology company, earning himself a fortune in the process.

Gates has since retired from the day to day functioning of Microsoft and focuses his efforts on his philanthropic causes through the Bill & Melinda Gates Foundation. These causes have included producing a malaria vaccine, gun control reform and education reform. The Foundation has a substantial portfolio of investments. Its investment philosophy is to use capital from the Foundation to help businesses create solutions to complex and entrenched problems. The following are some of the Foundation’s most prominent holdings, as of the date of the last reported SEC filing for Q2 2018. All market cap and pricing info is accurate as of August 17, 2018.

1. Berkshire Hathaway, Inc.

The largest holding in the Foundation’s portfolio is Berkshire Hathaway, Inc. (NYSE: BRK.B). The Foundation holds nearly 54 million shares of Berkshire Hathaway with a market value of just under $10 billion, for a portfolio weighting of 45.2%. The foundation decreased its Berkshire Hathaway holding in the third quarter by around 5 million shares, or 8.54%.

Berkshire Hathaway is one of the largest companies in the S&P 500 with a market cap of $511.84 billion and was ranked second in the 2017 Fortune 500 list. Bill Gates has developed a very close relationship with Warren Buffett since they first met in 1991; Gates serves on the Board of Directors of Berkshire Hathaway. Both investors have signed a pledge to give away a significant portion of their wealth to philanthropic causes.

2. Microsoft

The second largest holding is the company Gates founded. The foundation holds 32 million shares of Microsoft, with a market value of nearly $3.12 billion, for a portfolio weighting of nearly 14.3%.

Microsoft is one of the biggest companies in the S&P 500 with a market cap of $825 billion and was ranked 28th on the 2017 Fortune 500. The foundation trimmed its stake in Microsoft during the second quarter, selling 8 million shares or 20%.

3. Caterpillar

Caterpillar (NYSE: CAT) is the third largest holding in the Foundation's portfolio. The Foundation holds over 11 million shares of Caterpillar, with a market value of over $1.5 billion, for a portfolio weighting of just under 7%.

Caterpillar is a Dow stock and the maker of heavy equipment used for mining, agriculture and energy. It has a market cap of $86.48 billion. Caterpillar is ranked 65th on the 2017 Fortune 500.

4. Waste Management, Inc.

Waste Management, Inc. (NYSE: WM) is the fourth-largest holding in the Foundation’s portfolio. The Foundation owns over 18.6 million shares with a market value of $1.52 billion. Waste Management has a weighting of 6.85% in the Foundation’s portfolio, just beneath Caterpillar's 6.91%. 

Waste Management is a provider of waste management and associated environmental services. It further develops and operates waste to energy and landfill gas to energy facilities in the United States. It is the largest waste management company in the country with over 21 million customers. The company has a market cap of over $39.55 billion. Waste Management is ranked 202 on the 2017 Fortune 500.

5. Canadian National Railway Company

The fifth-largest holding in the Foundation’s portfolio is the Canadian National Railway Company (NYSE: CNI). The Foundation has over 17.1 million shares with a market value of $1.4 billion for a portfolio weighting of 6.3%. 

Canadian National Railway provides integrated transportation services including rail, trucking, freight forwarding and warehousing. The company mainly transports petroleum products, grain and fertilizers, coal, metals and automotive products. It has a market cap of $65 billion.