CNBC commentator Ron Insana advises that even though it is a volatile time in the markets, investors shouldn’t make hasty moves right now.

While he admitted that uncertainty about China, Greece, the Federal Reserve’s rate-hike plans, the dollar’s ability to sustain its strength and the weak Dow transports are “reasons to be cautious,” investors shouldn’t rush to change their strategy.

“You stay where you are,” he told CNBC. “Big names like Disney and Comcast are doing quite well. Starbucks is doing fine. McDonald's rebounded of late. Both of those have worked reasonably well,” he said.

“I don't think it's panic time. I would start watching the transports more closely now that they are breaking down further to see whether or not that's the type of theory that one needs to worry about. You have to pay attention here,” he said.

“You have to watch the headlines,” he said. “They are going to make this market — as we’ve seen in many summers past — a little more volatile than we enjoy.”

But MarketWatch columnist Jeff Reeves does see possible danger ahead.

"I remain a long-term bull and extremely optimistic about the U.S. recovery for this year and beyond," he writes. "But that doesn’t mean denying the risks that threaten the economy and stocks."

Among the ones he mentions:

• "Valuations are stretched." Robert Shiller's cyclically-adjusted price-earnings ratio for the S&P 500, which includes 10 years of earnings, stands at 27.4. That trails only the pre-market crash levels of 1929, 2000 and 2007.
• "Earnings pressure." Analysts expect a first-quarter profit drop of 4.1 percent for the S&P 500, according to FactSet. "Taken alongside valuation concerns, investors should take this Q1 earnings season quite seriously," Reeves says.
• "Retail sales still challenged." They fell in three of the last four months, and rose by a smaller-than-expected 0.9 percent in March.

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