Nasdaq 5,000: Bubble or not?

The Nasdaq index has rallied to levels matching its dotcom boom glory days, spawning a CNBC smackdown over whether the bubble is back too.

The bubble camp came out swinging.

"The Nasdaq wouldn't be here if not for quantitative easing. It wouldn't be here without zero percent interest rates. It wouldn't be here without unprecedented stock buybacks fueled by cheap money," Peter Schiff, CEO of Euro Pacific Capital, told CNBC. "You have all these artificial props which have lifted up the market and there's no way to sustain the market without those props."

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The Nasdaq index last touched 5,000 in March of 2000, marking the peak of the dotcom bubble's euphoria -- or what some called hysteria -- before the index crashed around 80 percent to a nadir of 1108.49 in October of 2002. It's been a long climb back to its 5008.096 close on Monday.

What bubble?

But not everyone is convinced dotcom euphoria is making a revival.

"I'm not a perma-bull. I'm very interested in shorting overhyped, overvalued stocks," Wayne Kaufman, chief market analyst at Phoenix Financial, told CNBC, citing bets against GoPro and Tesla. "I don't believe we are in a bubble and I think the fundamentals bear that out," he said, citing then-and-now data.

"Back in 2000, you had no free cash flow yield, no dividend yield and no equity yield," Kaufman said, citing price-to-earnings ratios that were sometimes as high as 200. But now, the S&P information-technology sector has a price-to-earnings ratio of 19.6 times, while the semiconductor index has a dividend yield of 2.1 percent, above the 10-year U.S. Treasury yield and even the S&P 500's 1.95 percent dividend yield, he noted.

Same old story

But Schiff's bubble camp isn't convinced by argument that the Nasdaq is different this time.

"There's never a bubble where it isn't different this time. That's how bubbles work and that's the one thing they all have in common," Schiff said. "Tech is not as overvalued relative to the rest of the market as it was in 2000, but that doesn't mean it's not a bubble."

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Schiff cited concerns overvaluation of some "hot" names, such as Uber.

"The valuation is absurd. And there's a lot of companies like Uber that are sporting these billion-dollar market caps. Many of these companies haven't made any money; many of them won't make any money," Schiff said. "This time around the difference is it's not a tech bubble, the entire U.S. economy is one gigantic bubble."

The Fed will do what?

Bryan Thomas | Getty Images

To be sure, Schiff's bubble argument has some hiccups. For one, he predicts that rather than raising interest rates -- as the market widely expects will happen this year -- the Federal Reserve will actually go for more quantitative easing. But he also expects that rising interest rates will decimate tech companies' free cash flow as they try to service the "enormous" debt they've taken on.

Tech start-ups typically raise venture capital or equity, not debt, and the rates on debt issued prior to a Fed hike likely wouldn't change.

—By CNBC.Com's Leslie Shaffer; Follow her on Twitter @LeslieShaffer1