NEW YORK ( ETF Expert) -- On Friday, August 17, the CBOE S&P 500 Volatility Index, or VIX, hit a three-year low. Apparently, options investors had not been feeling a need to purchase "puts" to protect against a devastating decline in U.S. stock prices.However, since logging a three-year low, the VIX has jumped roughly 25% (8/17/12-8/29/12). In the same time frame, the U.S. market has moved sideways (-0.4%). The VIX essentially measures the level of "put" activity over a period of 30 days. With that knowledge, one can surmise that options investors fear the Federal Reserve won't signal a third round of quantitative easing, or QE3. At the very least, there are those who worry that the stock market won't react favorably to whatever Fed Chairman Bernanke says this Friday in Jackson Hole. Equally worthy of note, the VIX is testing its short-term 50-day moving average. Technically speaking, a sustained breakout above this level could precede a pullback in the SPDR S&P 500 ( SPY).