Meanwhile, the CBOE S&P 500 VIX Volatility ( VIX), a gauge that typically moves in the opposite direction of the SPDR S&P 500 Trust ( SPY), is holding above a 50-day and 200-day moving average. What may be more remarkable than the interest rate story is the high probability than something else is weighing on common stocks -- something other than the overstated possibility of Fed tapering its bond binge. In other words, the 10-year yield may dip back to 2% or below in the near future, but that may not be enough to encourage a stock rally. The other story? The Japanese yen may cease to depreciate further and begin recovering against world currencies; that would effectively end the "carry trade" used to finance the purchase of higher-yielding and higher appreciating assets. In fact, the CurrencyShares Yen Trust ( FXY) often moves in the opposite direction as the SPY. Granted, it still makes sense to keep an eye on the direction of interest rates. If the 10-year moves significantly higher than 2.25% (a possibility that I regard as improbable), rate-sensitive income producers would feel even more pain. Still, if you really want to know whether U.S. stocks can withstand the pressure cooker, track the FXY. If the yen tracker manages to stay above its intermediate-term, 100-day trendline, and climb even higher, U.S. stocks may find themselves in the same downward spiral that other asset classes have already experienced. Follow @etfexpertThis article was written by an independent contributor, separate from TheStreet's regular news coverage.