Bloomberg tracks the fortunes of some 2,800 billionaires. Of those, 145 are worth at least $10 billion, making them decabillionaires. Now, the world contains two centibillionaires simultaneously.

Microsoft Corp. co-founder Bill Gates, once the world’s richest person, has again eclipsed the $100 billion threshold, joining Amazon.com Inc.’s Jeff Bezos in the exclusive club, according to the Bloomberg Billionaires Index.

Gates’s fortune, now $100 billion on the nose, hasn’t reached such heights since the dot-com boom, when Bezos was only beginning his march up the world’s wealth rankings. The Amazon founder is now worth $145.6 billion, having added $20.7 billion this year alone, while Gates has gained $9.5 billion.

These two fortunes underscore a widening wealth gap in the U.S., where those with the most capital are accumulating riches the fastest. It’s also a worldwide trend. France’s Bernard Arnault has an $86.2 billion fortune, equal to about 3 percent of his country’s economy. The net worth of Spain’s Amancio Ortega represents 5 percent of that nation’s gross domestic product. And then there’s Bidzina Ivanishvili, whose worth about a third of Georgia’s GDP.

The Gates and Bezos mega-fortunes may not last long. Gates has donated more than $35 billion to the Bill & Melinda Gates Foundation and said he intends to give away at least half of his wealth. Bezos, meanwhile, may be about to cede some of his fortune for a different reason: he and his wife Mackenzie are divorcing.

Bloomberg Billionaires Index ranks the world’s 500 wealthiest individuals. This year’s biggest losers in that group include Tesla Inc. Chief Executive Officer Elon Musk.