Microsoft’s founder and former chief executive, Bill Gates, became the world’s second ‘centi-billionaire’ after his fortune reached the $100 billion.

Amazon’s founder Jeff Bezos, who first attained that status in November, is estimated to be worth $145.6 billion.

According to Bloomberg, which tracks the wealth of the planet’s richest people through its Billionaires Index, the Microsoft co-founder has already earned $9.5 billion so far this year – taking him right up to the magic $100 billion marks.

Bezos, who started e-commerce marketplace Amazon in 1994, has amassed a staggering $20.7 billion since January 1.

The Gates and Bezos mega-fortunes may not last long. Gates has donated more than US$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’s Chief Executive Officer Elon Musk.