MONTREAL–Life is tough if you're a billionaire – these days at least.

Amid a global recession, Canadian billionaires, like their global counterparts, have been shorn of shockingly huge chunks of their net worth, while others are no longer billionaires at all.

According to Forbes Magazine, which made its annual compilation of billionaires public tonight, 355 of the world's ultra-rich dropped off the rarefied list, including five from Canada. It's the first time since 2003 that the number of billionaires in the world actually shrank. There are 793 billionaires in the world, compared to 1,125 last year. Canada has 20.

"The people on the billionaire's list, maybe 95 per cent of their wealth or more is in stocks and shares," said Jim Davies, professor of economics at the University of Western Ontario. "And so with all these indexes down by about 50 per cent, you could make a rough guess what would happen to your average billionaire. I'd expect they'd lose half their wealth compared to a year earlier."

Topping Canada's list like last year was the Thomson family, involved in various media ventures and information distribution company Thomson Reuters, with a net worth of $13 billion (U.S.), significantly down from last year's estimate of $18.9 billion.

Next is Galen Weston of food giants Galen Weston Ltd and Loblaw Co., with a net worth of $5 billion. That's down from $7 billion last year.

The Irving family of Saint John, N.B., owners of oil, forestry and newspaper companies, came in third at $3.9 billion, down from $6.7 billion.

Montreal's Paul Desmarais and Guy Laliberte, founder of the famous Cirque du Soleil, rounded out the top five.

Laliberte was the only Canadian billionaire – and one of just 44 in the world – whose net worth actually increased in the last year. Part of that is the result of his sale of 20 per cent of his dramatic stage enterprise to an investment arm of Dubai World and a real estate developer Nakheel. Laliberte kept more than $400 million from the deal, according to Forbes.

The richest man in the world was once again Microsoft founder Bill Gates, who lost that enviable perch to investor Warren Buffet last year. Even though he lost $18 billion over the last year, he is still worth $40 billion. Buffet lost $25 billion from the value of his company Berkshire Hathaway, and is now worth $37 billion.

The total net worth of all the billionaires is down nearly by half, off $2 trillion to $2.4 trillion.