Internet and biotechnology stocks have surged higher in recent months, leading some investment experts to conclude that bubbles are arising in those sectors.

The S&P Biotechnology Select Industry Index has gained 37.8 percent over the last year, and the S&P North American Technology Internet Index has risen 40.4 percent.

"There are definitely speculative excesses in the market right now," hedge fund manager Doug Kass, president of Seabreeze Partners Management, told The New York Times.

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"I don’t think the whole market is in a bubble. But in biotech and some of the Internet stocks, there’s no question. We’ve certainly got bubble-like symptoms."

The IPO market also looks like a bubble, Kass said. "And that’s serious, because that’s where the first signs of the bear market that started in 2000 began."

As for the biotech sector, it accounted for 45 percent of IPOs in the first quarter, and none of those companies were profitable, Jay Ritter, a business professor at the University of Florida, told The Times.

"In social media and biotech, a lot of companies seem to be based on hopes and dreams, not revenue or earnings," Ritter said.

Investors are starting to rotate out of growth stocks and into value stocks.

"It is comforting that the rotation [out of expensive stocks] doesn’t seem to have had an impact on the index level as a whole," William de Vijlder, chairman of BNP Paribas Investment Partners, told the Financial Times. "In some ways it is a vote of confidence that [investors] are happy owning value stocks instead."

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