Koesterich says volatility looks to set to heat up this summer, so he favors defensive sectors such as healthcare and cutting exposure to small-cap stocks.

Volatility is simply too low, he argues. “Over the past 20 years volatility on U.S. large cap stocks has averaged around 20% a year,” he wrote. “Given the current environment, which is characterized by the continuing unrest in the Middle East, the lingering US sovereign debt issues, and the lingering European sovereign debt issues, it is hard to justify below average volatility.”

Although the S&P 500 is about flat over the past month, the real story for U.S. stocks has been about sector rotation, says Nicholas Colas, ConvergEx Group chief market strategist.

“Investors have forsaken old favorites (silver ETFs and energy stocks, for example) and migrated to the unloved (healthcare), ignored (utilities) and boringly stable (consumer staples),” Colas wrote in a note to subscribers Tuesday. “The same dynamic has been working its way through the options market, repricing risk as market attention shifts.”

ProShares VIX Short-Term Futures (NYSEArca: VIXY)