What just happened? 2020 has been an annus horribilis for most people, but it's been a pretty good year for Elon Musk. The CEO sat in 35th position on Bloomberg's Billionaire Index in January. Now, thanks to another surge in Tesla's share price, Musk has passed Bill Gates to become the second-richest person in the world.

It was only last week when Musk saw his wealth increase by $15 billion following Tesla's acceptance into the S&P 500, which measures the stock performance of 500 large companies listed on the US stock exchanges. Musk, who owns 20 percent in the EV giant, saw his personal fortune leap to $117.5 billion as Tesla's shares hit $408, taking Mark Zuckerberg's 'third-richest person in the world' title in the process.

Tesla's shares closed up 6.58 percent at $521.85 yesterday, pushing Musk up to $127.9 billion and putting him above second-place Bill Gates ($127.7 billion). That's still a long way off Amazon head Jeff Bezos and his $182 billion worth, of course.

Bloomberg notes this is only the second time in the index's eight-year history that Gates has ranked lower than second place, though the former Microsoft boss' wealth would be higher had he not donated more than $27 billion to charity since 2006 through the Gates Foundation.

Musk has made more money this year than anyone on the planet

Musk does top the list when it comes to the largest net worth increase in 2020, having added $100.3 billion to his already vast fortune.

Musk and Gates certainly don't appear to be billionaire buddies. The former has famously downplayed the threat of the Covid-19, something which incurred Gates' wrath. He called Musk's comments on the virus "outrageous," while the SpaceX billionaire has mocked Gates on Twitter.