In a year in which the U.S. elected a multi-billionaire property developer as president, the ultra-rich as a group have done very well, especially American billionaires, Bloomberg reports. The 500 wealthiest people in the world had a combined net worth of about $4.4 trillion, an average of $8.8 billion each, as of December 27. Four of the five biggest gainers in 2016 are Americans.

As a group, though, the 500 billionaires posted increases that trailed the market averages.

Born in the U.S.A.

Warren Buffett, the legendary investor and chairman of Berkshire Hathaway Inc., was the biggest winner, up $11.8 billion, or 19%. With a total net worth now at $74.1 billion, he is once again the world’s second-richest person, according to Bloomberg.

Microsoft Corp. (MSFT) founder Bill Gates remains the world’s wealthiest person, with $91.5 billion. He gained $9.8 billion. Oilman Harold Hamm (up $8.4 billion) and Jeff Bezos, founder and CEO of Amazon.com Inc. (AMZN) (up $7.5 billion) were the other Americans in the top five year-to-date gainers through December 27. For more detail, including daily updates of the net worth of the top 200, see Bloomberg Billionaires.

Trump's Gift to Political Enemies

In an ironic twist, the post-election Trump rally has added about $77 billion to the coffers of American billionaires, most of whom opposed Trump, according to Bloomberg. Buffett, in campaigning for Hillary Clinton, was scathing in his criticisms of Trump. Shares of Berkshire Hathaway (BRK-A), got a big boost from holdings in airlines and banks that soared after Trump's victory. The surging market proved other anti-Trump billionaires woefully wrong. Tech entrepreneur Mark Cuban, the rabidly anti-Trump owner of the Dallas Mavericks of the NBA, in May forecast a 20% stock market slide if Trump were elected.

Indexes Beat the Billionaires

The 500 billionaires tracked by Bloomberg have enjoyed a collective gain of about 5.7% so far in 2016. However, that gain badly trailed the major market indexes. For example, the Dow Jones Industrial Average (DJIA), the S&P 500 Index (SPX) and the Russell 2000 Index all have posted double-digit gains this year. In fact, when the Bloomberg Billionaires database is sorted by year-to-date returns, only 69 of the 200 persons listed, or 34.5%, have enjoyed investment returns of 10% or more in 2016.

Of course, many of these people owe their wealth to founding companies, and their investment portfolios thus are concentrated in shares of these firms and lack diversification. On the other hand, this can be taken as evidence of how even the world's richest and presumably best-informed investors don't always beat the market. (See also: Passive Funds are Killing Active Money Managers.)

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