The magazine put his net worth at $3.5 billion, down $1 billion from the rankings it issued a year ago.
As a result, his position on the Forbes' ranking dropped 220 spots, leaving him tied with 19 others as the 544th richest person in the world.
Forbes said that much of the decline in Trump's net worth is due to softness in the midtown Manhattan real estate market.
The 2017 list is longer than it's ever been before -- Forbes estimates there are now 2,043 billionaires worldwide, up from 1,810 in 2016. Their average net worth is $3.75 billion, which means Trump is not even worth as much as the "average" billionaire.
I sense a tweet storm coming.