The S&P 500 may have tripled over the past six years, but that doesn't mean it's out of control, says legendary hedge fund manager Leon Cooperman, founder of Omega Advisors.

But the bond market, which has soared over the past 34 years, that may be a different story, he says.

"I think the [stock] market’s ok. It’s not cheap, but it’s not priced to perfection," he said on PBS' "Wall Street Week" Sunday. "The bubble is not in the stock market. If there’s a bubble, it’s in the bond market."

The S&P 500 carried a trailing price-earnings ratio of 21.23 Friday, up from 18.50 a year earlier, according to Birinyi Associates.

So why are stocks generally safe? Because three of the four historic prerequisites for a crash aren't in place, Cooperman says.

The four:

• 1. Investors "smell an oncoming recession,"
• 2. The market turns "frothy," as investors get "exuberant,"
• 3. Geopolitics turn sour,
• 4. The Federal Reserve "takes the punch away from the punch bowl."

Only No. 3 is a risk now, Cooperman says.

Another hedge fund heavyweight, Doug Kass, president of Seabreeze Partners Management, isn't so sanguine.

The stock market "looks serene gliding across the pond, but underneath the surface it's furiously paddling. . . . There's massive turmoil," he writes on TheStreet.com.

Kass cites several bearish signals.

• "New 52-week highs have been declining in every rally since February;"
• S&P 500 stocks trading above their 200-day averages have reached lower highs in every rally since last September;
• "Healthcare and technology are the only major sectors even close to maintaining breadth and momentum;"
• Utilities peaked in the late week of January and are now almost 10 percent below that top;
• "Energy stocks topped out in April 2014 and today are about 21 percent below that peak;"
• Transports touched their highs in November and broke major support levels last week, falling 17 percent below their highs.

Bottom line: "It's almost as if Daffy Duck has taken over the market's pond these days," Kass says. "Let's call this the Summer of Looney Tunes."

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