This column has remarked before that nothing in financial markets is as risky as a safe bet.
That might sound screwy, but there are some good reasons for it.
If a particular trade is widely regarded as a sure-fire money-maker, then it is likely that everyone who wants to buy in has already done so.
And if all the potential buyers are already fully invested, that means there are no more buyers out there and no new money coming in to propel the price higher.
But with everyone long, there are plenty of potential sellers. As a result, there is only one way for the price to go: down.
This idea, of course, is the basis of contrarian investing. If everyone is in love with a stock or a market, it is probably overbought and primed for a fall. Similarly, if everyone agrees a particular asset is a dog, then it is almost certainly over-sold and ready to rally.