Amazon.com CEO Jeff Bezos is now the richest person of all time, with a fortune of $105.1 billion, according to financial news outlet Bloomberg.

With the stock market soaring to new heights in the first few days of 2018, Bezos’ fortune rocketed upward, growing $6.1 billion in just five trading days.

That happened because most of Bezos’ wealth is contained in shares of Amazon.com, the online retail giant. Shares of Amazon rose 56 percent in 2017 and more than 6 percent since the start of this year.

Financial news trackers differ on whether Bezos is the richest man in history, or if his nearest rival, Microsoft founder Bill Gates, holds that record.

Bezos surpassed Gates briefly last year before taking the lead for good in October and crossing the $100-billion mark by November, buoyed by the holiday shopping season.

Gates is worth more than $90 billion, but financial experts say he would be worth far more if he had not given away so much in cash and shares of Microsoft to charity. Bloomberg reports that if Gates had not given away some $36 billion of stock to charity, his fortune would be worth more than $150 billion.

In addition to Amazon, Bezos’ holdings include The Washington Post and the space exploration company, Blue Origin.