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Cramer: I get nervous when price targets double

Cramer: What's making me nervous

The stock market has split into two camps right now, CNBC's Jim Cramer said Tuesday. One based on eyeballs and hype, he said, and the other based on basic investing fundamentals and traditional metrics.

"You can't have two stock markets at once," he said on "Squawk on the Street." "It doesn't work."

Cramer highlighted that Morgan Stanley doubled its price target on electric carmaker Tesla Motors to $320 a share Monday, setting up the stock for huge gains. He lauded both the Morgan Stanley analyst who made the call and Tesla CEO Elon Musk, comparing the forward-thinking entrepreneur to Henry Ford and Thomas Edison.

Still, that kind of exuberance makes Cramer uneasy.

(Read more: Tesla soars, Ford falls in 'Consumer Reports' study)

"I get nervous when I see price targets double," he said. "I get nervous because we've been around when price targets double and stocks don't double along with the price target."

People are too impressed with high tech: Shiller

Nobel laureate Robert Shiller, a professor of economics at Yale University, also expressed concern about the current trajectory of the stock market, telling CNBC that it draws parallels with the dot-com bust of the early 2000s.

(Read more: Cramer: Finally! A retailer that can beat Amazon)

"We do have a little bit of bubble thinking," Shiller said on "Squawk on the Street." "I'm thinking also of bitcoin. That one has burst in a way. People are very impressed by high tech. Probably too impressed."

Shiller, who developed his own price-to-earnings ratio based on longer-term data, said companies such as WhatsApp belong in a "different market." An instant messaging service with more than 450 million users, WhatsApp agreed to an acquisition by Facebooklast week for $16 billion.

(Read more: Why Facebook valued WhatsApp at $16 billion)

"It's for adventurers," he said of the tech and social media sector. "I'm more of a stable investor who looks at long history and wants to invest for the long term. So maybe ask someone else about these upstart companies."

—By CNBC's Jeff Morganteen. Follow him on Twitter at @jmorganteen and get the latest stories from "Squawk on the Street."