Back on Nov. 30, I wrote about the bullish move in the dollar and how large speculators were shifting from a net short position to a net long position. Since that time, the dollar has been caught in a range.

In the meantime, the large speculators have shifted their opinion as well. After moving to a net long position, they shifted back to a net short position and have now moved back to a net long position.

During the last five years when large speculators have shifted their opinion on the dollar so drastically, the currency has rallied. At this time, it looks like the dollar index could rally a good 10 percent.

While this may not seem like a big deal when you consider the moves made by stocks and commodities from week to week, a 10 percent move in the dollar index is rare.

If you don't have a currency account, there is a way to play a rally in the dollar with an ETF. The PowerShares DB US Dollar Index Bullish Fund (UUP) is an ETF that tracks the US Dollar against a basket of other currencies.

If the UUP can move up 10 percent over the next four or five months, it would put the ETF above 25 for only the second time in the last year and a half.