Uncertainty for stocks remains. What to buy

Traders work on the floor of the New York Stock Exchange.
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The market reacted strongly Monday to the possibility of a smooth Greece resolution, but if history is any guide, there is much more tumult out of the E.U. ahead.

That, coupled with an ever-changing timeline for when the Federal Reserve will raise rates, could mean that stocks are in for a bumpy ride during the second half of the year.

Since late February, the S&P 500 traded sideways as investors remain cautious over the faith of this six-year bull market, which is now the third-longest in history.

Market watchers have increasingly pointed to the negative seasonal track record for stocks during the summer months along with news from Greece and the Fed as potential triggers for the market to sell off.

"We believe increased volatility is likely to persist throughout the year and beyond," warned Brian Belski, chief investment strategist at BMO Capital Markets, in a recent note to clients.

The most-watched gauge of market volatility—the CBOE Volatility Index—remains quite subdued, remaining basically below the 16 level since January.

Jim Strugger, derivatives strategist at MKM Partners, wrote this month that "it is unlikely that U.S. equities can sustain a breakout to fresh all-time highs without first cycling through a period of higher volatility."

So how should investors play the uncertainty in the market?