By Ian Campbell
The author is a Reuters Breakingviews columnist. The opinions expressed are his own.
Many emerging economies have been banking on weaker currencies to revitalise economic growth. Oil's 25 percent fall in dollar terms this year should also help. The problem however is the dollar's strength which is leading to a general tightening of monetary conditions worldwide, more so in countries where central banks are intervening to prevent their currencies from falling too much.
When the U.S. Federal Reserve launched its third round of quantitative easing, or QE3, it was hailed as an "open-ended" policy that would last as long as needed. Most important for investors, the pace of the bond buying - which started at a somewhat arbitrary $85 billion per month - would be "data dependent." Especially throughout the spring, officials stressed they were serious about adjusting the dial on QE3 depending on changes in the labor market and broader economy. But as the unemployment rate dropped to 7.3 percent last month from 8.1 percent when the program was launched in September, 2012, the bond-buying has effectively been on auto-pilot for 14 straight months.
Four years into the stock market party fueled by a punch bowl overflowing with trillions of dollars of central bank liquidity, you'd think a hangover might be looming.