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RBS's Andrew Roberts challenged to put his money where his mouth is

Market Economics managing director Stephen Koukoulas has challenged the Royal Bank of Scotland's Andrew Roberts to put his money where his "sell everything!" mouth is – and under generous terms for the RBS Doomsday forecaster.

In shades of the great Rory Robertson v Steve Keen "Australian housing prices will crash" bet, Koukoulas has offered the RBS credit chief a $10,000 wager over the latter's prediction that this is the year that mostly everything falls.

And Roberts has to be right about only six of a designated 11 markets to collect the $10K – which looks like vastly better odds than any American Powerball game. Six out 11 is a long way short (so to speak) of "mostly everything".

Koukoulas' 11 chosen variables are the main indices for the stock markets of the US, Brazil, China and Japan, plus house prices in the US, UK and Sydney, oil, iron ore, copper and the Australian dollar. If just six of those are lower on December 31 than they were on Wednesday, Roberts gets the Australian economist's cash.

Given that "The Kouk" made the challenge on Wednesday, he's in effect offering Roberts a flying start after overnight falls, but Roberts hasn't replied. A Twitter suggestion was that Roberts might have already sold his mobile phone.

After gaining so much international attention for RBS, Roberts might wish the matter would quietly go away – but Koukoulas has promised to regularly update readers of his tweets and web site on whether the challenge is taken up, and how the bet is progressing.

Poor old RBS – it looks like none of the 11 variables are ones that the bank can attempt to fiddle any more