The stock market is at risk of plunging amid negative fundamentals, says Lance Roberts, CEO of Streettalk Advisors.

The Standard & Poor’s 500 Index already has dropped 8 percent since the beginning of May, to 1,278 at Friday's close. Roberts tells Yahoo the next key support for the index stands around 1,200 to 1,250.

"If we get below 1,200, we have to have another conversation."

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Europe’s debt crisis and U.S. economic struggles are weighing on the market. The U.S. government reported Friday that payrolls gained only 69,000 in May.

But Roberts thinks stocks are likely to rebound this month. What’s happening now is a correction to the first quarter’s outsize gains, he says.

But, “June tends to be a positive month after a bad May, so … there’s very likely to be a rally in June.” If that occurs take advantage of the opportunity to sell your losers and trim back on big gainers, Roberts says.

"Generally after a big sell-off, you get one good bounce, another sell-off, and that's where you're going to find your buying opportunity, most likely sometime between August and September," he says.

Others see buying opportunities, too. “People are going to find value,” John Lynch, regional chief investment officer for Wells Fargo Private Bank, tells Bloomberg.

“Our fundamentals may be declining, but our fundamentals are less absurd than in many areas of the world. Profits are at record levels. That’s an opportunity for the longer-term investor.”

Editor's Note: This Wasn’t an Accident — Experts Testify on Financial Meltdown