Just a few days ago was the 80th anniversary of the stock market crash. October 29, 1929, or "Black Tuesday" was the day that resulted in banks collapsing and the once-roaring US economy sinking into the Great Depression.

As we think back to the worst stock market collapse ever, it might be time to wonder whether we are headed for another major bust. That's the warning from economist Nouriel Roubini in the Financial Times where he says the marked rally in risky assets - equities, oil, energy and commodity prices - combined with a sharp drop in the dollar, tightening credit and and increase in bond yields are danger signs.

The problem, Roubini says, is that its being funded by a tanking US dollar which has become the funding currency for these trades. If the dollar starts to appreciate and the US economy starts to surprise everyone by growing again, there will be a stampede and it will be ugly.

Roubini writes: "This unraveling may not occur for a while, as easy money and excessive global liquidity can push asset prices higher for a while. But the longer and bigger the carry trades and the larger the asset bubble, the bigger will be the ensuing asset bubble crash. The Fed and other policymakers seem unaware of the monster bubble they are creating. The longer they remain blind, the harder the markets will fall."