Amazon Founder Jeff Bezos, already the world’s richest man, has gotten even wealthier recently—adding an eye-popping $10 billion to his net worth in less than two weeks.

According to the Bloomberg Billionaires Index, Jeff Bezos’s net worth was $99 billion on New Year’s Day 2018. One week later, Bezos hit the $105 billion mark, making the Amazon founder and CEO richer than Microsoft founder Bill Gates had ever been, at least in nominal terms.

Facebook Founder Mark Zuckerberg earlier this week was announced to her made $4.4billion just as the year started.As of the close of the stock marketon Friday, Bezos’s net worth hit the $109 billion mark, according to Forbes. In other words, Bezos has made $10 billion so far in 2018—and we’re not even two weeks into the year.

Jeff Bezos’s wealth is based mostly on his ownership of Amazon stock.

And Amazon shares have climbed steeply in 2018, adding a mind-blowing $1 billion per day to Bezos’s net worth this week alone. On Friday, Amazon stock rose by more than 2%, topping $1,305 per share. That’s up from around $1,170 at the start of 2018.For a little perspective, Bloomberg estimated Thursday that Bezos’s net worth (then a mere $108 billion) was the equivalent of 0.577% of GDP for the entire United States. It was also 1.8 million times higher than the median household income in the U.S.