Forget "sell in May and go away"—investment strategist Carmine Grigoli told CNBC Friday that he expects the market to "explode to the upside" over the next couple of months.
"Interest rates are falling, profit growth is accelerating … and M&A activity is soaring," he told CNBC's "Power Lunch."
Grigoli, chief investment strategist at Mizuho Securities, thinks that adds up to a 10 percent to 12 percent rally by year's end.
Historically, May through September tend to be the weakest months for the market.
Read MoreWhat does 'sell in May and go away' mean?
Although Jim McDonald, chief investment strategist at Northern Trust, sees "acceptable value" in the market, he isn't as bullish as Grigoli.
"There has got to be better evidence the U.S. can break out of this 2 to 2.5 percent growth pace," he said. "We're seeing some positive signs on credit creation but the housing market is going nowhere fast, so we're not that excited about the upside potential."
Gross domestic product only expanded at a 0.1 percent rate for the first quarter, a sharp pullback from the fourth quarter's 2.6 percent pace.
Read MoreThe ripple effects of housing's fading rebound
McDonald thinks the rotation out of momentum names into "tried and true" stocks will continue for the next couple of quarters until there is "clear evidence about the re-acceleration of the U.S. economy."
There is still value to be found, he said, but "there aren't big pockets of cheap stocks today."
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So where can investors find that value? For McDonald, it's in U.S. equities and U.S. high-yield debt.
"High yield is a good example of the canary that is not getting woozy from gases coming out in the coal mine," he said. "We think that the spread tightness there is justified and likely lead to reasonable returns going forward."
Grigoli likes consumer staples and tech, specifically larger-cap, high quality names in biotech, software and Internet, which have seen some big corrections.
—By CNBC's Michelle Fox. CNBC's Jennet Chin and Reuters contributed to this report.