He reportedly wrote: "It's not a billion. It's $3.3 billion since no one at Forbes knows how to count."
According to Forbes, Kanye was furious after the publication's annual World's Billionaires list - featuring his sister-in-law Kylie Jenner, whose billionaire status has since been removed - was published in March but there was no mention of him.
He is said to have texted: "You know what you're doing. You're toying with me and I'm not finna lye down and take it anymore in Jesus name."
Along with his share of the Yeezy footwear brand, which Forbes estimates at about US$1.4 billion, with a note that it's a "private, highly-illiquid US$1.4 billion" putting it closer to US$1.26 billion, Kanye also has US$17 million in cash and US$35 million in stocks.
He also holds US$81 million in "buildings and improvements", US$21 million in land and his G.O.O.D. label - along with his own recorded music and publishing rights - is worth at least US$90 million, according to documents provided by the rapper.
However, due to the "illiquidity of these myriad assets and the lack of independent backup", Forbes estimates that the assets are worth 50 per cent less than stated, leaving Kanye with about US$125 million in assets outside of Yeezy.
Additionally the magazine says that between "mortgages, advances and other liabilities", the rapper owes about US$100 million.