Bill Gates is still generating wealth.
"We're not in a defensive stance where most are in cash or something," Microsoft's founder said in an interview with Bloomberg Television. "The strategy used in investments is to have more than 60% in stocks."
The strategy helped Gates raise his net worth by $ 16 billion this year, raising his fortune to $ 106 billion, second only to Jeff Bezos on the Bloomberg Billionaire Index, even with his charitable donations of $ 35 billion.
Equity assets accounted for about $ 60 billion of Gates' fortune as of Monday, according to data compiled by Bloomberg. By comparison, the average North American family office portfolio held about 32 percent of its equity assets in 2018, according to Campden Wealth's 2018 global family office report.
The growth, managed by billionaire investment director Michael Larson, who runs family office Cascade Investment, allowed Gates to build the world's largest private foundation without diminishing his fortune.
But that fortune may begin to shrink if politicians comply with their request for higher taxes.
"I doubt the US will impose a wealth tax, but I wouldn't be against it," Gates said during the interview. "The closest we have to this is the property tax. And I've been a strong advocate that it should return to the 55% level a few decades ago."
Inequality has become a controversial political issue: America's richest 0.1% controls more wealth than at any time since 1929. On Tuesday, the Bill and Melinda Gates Foundation released its annual Goalkeepers report. The study seeks to monitor and assist United Nations progress towards its Sustainable Development Goals, which the foundation says are being undermined by persistent inequality. The report called for greater investment in health, education and technology to help reduce inequality in the world.
"There is no silver bullet that makes geography, gender and other random factors stop being important," the report notes. "But ensuring that all children have access to good health and education systems is a good start in this direction."
Gates, 63, has also supported higher income taxes on the richest in the US and has called for greater transparency. "I advocate more financial transparency. I don't like you having trusts where nobody knows who owns them."
While Gates remains optimistic about the US and the global economy, he doubts that his past performance will persist. "There is reason to think that absolute returns for the next decade will be lower than they were in recent decades."