Japan Desperately Needs a Stronger Dollar, China Desperately Wants a Weaker Dollar: The Fed Can’t Please Both

http://www.oftwominds.com/blogapr16/yen-yuan-USD4-16.html

Foreign exchange (FX) is a zero-sum game: if one currency weakens, another must strengthen. Since the value of a currency is relative to other currencies, all currencies can’t weaken together: at least one currency must strengthen as others weaken.
That one strengthening currency has been the U.S. dollar (USD) since mid-2014. The USD has strengthened by 20%, while the Japanese yen and the euro weakened by 20%. Many developing-economy currencies (rand, peso, real, etc.) have fallen off a cliff, suffering 40% to 50% (or even more) declines against the U.S. dollar.
Why does any of this matter? Simply put, the stock market is a monkey on a leash held by central banks–just give the leash a little tug, and the monkey jumps. Bonds are a gorilla–harder to control, but still manageable–but foreign exchange is King Kong, trading $5 trillion a day and impossible to control beyond short-term manipulations.
Currencies set the underlying trend, not just for bonds and stocks, but for entire economies. A weakening currency makes a nation’s exports cheaper in other countries, and the theory is that expanding exports will boost the overall economy–especially if that economy is stagnating or in recession.