Yen has fallen 7.5% against the US dollar - BBH

Analysts at Brown Brothers Harriman explained that since the US election nearly a month ago, the Japanese yen has been the weakest performing major currency. 

Key Quotes:

"It has fallen 7.5% against the US dollar.  

At the risk of oversimplifying, there is one major drag on the yen, and that is rising US interest rates.  Consider that the correlation between the US 10-year generic yield and the dollar-yen exchange rate.  The correlation between the level of US rates and the exchange rate is near 0.98 over the past 60 days.  It appears to be the highest since at least 1990.  

When we run the correlation on the basis of the percentage change, the correlation drops to almost 0.60.  This is still the upper end of where the correlation has been over the past decade.  In the last five years, it has been above 0.70 only a couple of times.  

The correlation between the yen and US yields seems tighter than between the yen and the interest rate differential.  The correlation between the percent change of differential between US and Japanese 10-year interest rates and the dollar-yen exchange rate is around 0.57, near the lowest level four months.  The correlation on the level of the yen and the rate differential is at 0.97, which is the upper end of the multi-years range.  

How to reconcile these correlation studies?  The interest rate differential is important, but most recently the spread is driven by the US side of the equation.  Specifically, over the past month, the US 10-year yield has risen 66 bp, and the Japanese 10-year yield has risen almost 10 bp."