Still, Trump's wealth estimation on Forbes' list was higher than for Bloomberg's worldwide billionaires list, which estimated his worth at $2.86 billion.
As a candidate, Trump said his net worth was more than $10bn, but Forbes pegged that figure at $4.5bn in September 2015.
Trump did not campaign with the magazine in an effort to boost his ranking as he's done in years past, Luisa Kroll, Forbes magazine senior wealth editor, told CNBC.
"A tough NY real estate market, particularly for retail locations; a costly lawsuit and an expensive presidential campaign", all took a toll on Trump's finances in the past year, Forbes reported. One fellow billionaire Trump tapped for his presidential cabinet was among the less fortunate. By Forbes'estimates, his wealth has fallen 31 percent in two years.
Trump's business empire continued to run despite his ascendancy to the White House after he beat Hillary Clinton in the 2016 elections. Similarly, the value of Trump's minority stake in a downtown San Francisco office building rose with the city's hot real estate market, Forbes estimated.
Forbes has been following Trump's tremendous fortune since 1982, when the 400 wealthiest rundown appeared. But this may be his last year atop the mountain, as Amazon's Jeff Bezos, worth $81.5 billion, was again in the No. 2 spot for the second consecutive year and briefly vaulted Gates earlier this year.
Signaling an overall improvement in the fortunes of American entrepreneurs, 289 members of Forbes 400 witnessed an increase in their net worth, compared to 187 in 2016.