People must look at all their financial assets right now and say "I want to sell them or preserve them," as they're going to go down in value in the coming years, says Harry Dent the Founder of HS Dent Investment Management.

"Real estate, stocks, everything but the most conservative government, Australian and US Treasury Bonds, are going to go down to reality and it's going to hurt more than anybody thinks it ever could".

"And nobody thinks it could happen and I'm the only guy on earth saying it," Mr Dent told Sky News host Chris Smith.

"Once you get bubbles of this extent, there's no way to stop it, they have to come down to reality".

"I'm telling you, it's 30 to 50 per cent for real estate in most countries and it's 60 to 90 per cent in stocks in most countries.

"This is going to kill most people's retirement portfolios.

"And there's nothing they can do about it ... I'm telling you it's coming in the next two-to-three-years.

"And I think it's about to start in the next month or two."