Donald Trump may have won the top political job in the United States, taking the presidency in a hard-fought struggle against Hillary Clinton, but the people at Forbes magazine say Trump's financial status hasn't fared as well.

In the 30th anniversary edition of its annual listing of the world's billionaires, Forbes estimates that Trump's fortune has fallen over the past year by $1 billion US to $3.5 billion.

Trump hasn't released his tax returns, but during the election campaign he claimed to be worth in excess of $10 billion.

Forbes said it estimates Trump's net worth has fallen by $200 million since the November election that saw him claim the White House. In its worldwide rankings of billionaires, Forbes said Trump has slipped 220 positions to Number 544.

Manhattan real estate slumps

Much of Trump's slide, the publication said, is linked to a drop in the value of real estate in midtown Manhattan. Forbes said about 40 per cent of the president's fortune is linked to Trump Tower and other Trump-owned properties near to it.

While Trump's fortune is estimated to be down, Forbes said the average billionaire's fortune has grown by 16 per cent since the publication of the last edition of the rich list. That jump is partly attributed to the so-called "Trump bump," the post-election rally in stocks that helped push the Dow Jones industrial average through the 20,000-point plateau and sent other market indexes to record highs.

Forbes pointed out that Trump would likely have missed out on the stock market rally, as he indicated during the election campaign that he sold all of his stock holdings.

Rising oil prices are also cited as another key reason for the rise in the fortunes of some other of the wealthy people on the Forbes list.

Not all of the news is bad when it comes to Trump's financial situation, Forbes says. Midtown Manhattan is seeing something of a pickup, and the value of Trump's Mar-a-Lago retreat in Florida has gone up by an estimated $25 million.

The value of Trump's hotel management and licencing business is also estimated to be up by estimated $97 million, thanks to an overall improvement in the hotel market.

Gates remains on top

Overall, Forbes said the number of billionaires on its latest list grew by 233 to 2,043, with Bill Gates at the top for a fourth consecutive year. Gates' fortune is estimated to have increased to $86 billion, a jump from $75 billion last year.

Second on the list is U.S. investor Warren Buffett, whose fortune increased by $14.8 billion over last year to $75.6 billion.

Forbes said Amazon.com's Jeff Bezos had the biggest monetary increase on the list, with his fortune surging by $27.6 billion to $72.8 billion. That was enough to move Bezos to third on the list from fifth last year.

The Canadians on the Forbes list include: