Dollar to rally higher? The math doesn't add up

A trader works on the floor of the New York Stock Exchange.
Adam Jeffery | CNBC

Strategists see dollar bull continuing, but math suggests they could be wrong.

The upward run in the U.S. dollar to nearly 12-year highs shows the currency index could be reaching a peak soon, if history is any guide.

As of Tuesday's close, the dollar index was nearly 3 standard deviations above its 50-day moving average. Since 1986, the index has been in this position just 0.58 percent of all trading days, according to quantitative analysis tool Kensho. The probability of the index moving lower in the following days is 92.3 percent and the probability of the index moving higher is 7.7 percent.