Fear of a tech stock bubble has been growing as the Nasdaq has returned to its heights just before the dot.com bubble burst in 2000.

Experts say don't worry.

For one thing, the Nasdaq is not the same as it was in 2000, experts tell CNNMoney.

Editor’s Note: 5 Reasons Stocks Will Collapse . . .

"The Nasdaq has really grown up over the last decade. It's a lot more mature now," says Kim Forrest, senior equity analyst at Fort Pitt Capital.

Conventional perception equates the Nasdaq with tech stocks, but its composition has changed.

Tech stocks now make up 42 percent of the Nasdaq composite, down from 57 percent at the top of the dot.com bubble, CNNMoney reports, citing Nasdaq OMX data. The share of consumer services has grown from just 0.5 percent in 2000 to almost 22 percent, healthcare from about 4 percent to almost 14 percent and financials from about 4 percent to 7.3 percent.

"The Nasdaq is definitely not nearly as lopsided as it used to be," Ryan Detrick, senior technical analyst Schaeffer's Investment Research, tells CNNMoney. "Having more diversification gives the index a whole different feel, and helps its safety factor."

Apple makes up about 13 percent of the Nasdaq 100, the largest nonfinancial firms on the exchange, compared with 1 percent in 2000.

Amazon and Google are important players, while the influence of Cisco and Intel has faded. And we can't forget Facebook, not in existence in 2000, is now about 2.5 percent of the Nasdaq 100.

Biotech firms are more important factors. For instance, Gilead Sciences, not in the Nasdaq 100 in 2002, now represents almost 3 percent of the select group.

"Biotech companies are now making money, which wasn't so much the case a decade ago," Detrick explains. "And with the way the demographics are changing — aging baby boomers — biotech will continue to be one of the strongest sectors."

Today is completely different, agrees Mark Hulbert, founder and editor of Hulbert Financial Digest, in an article for MarketWatch.

The price-earnings (P/E) ratio based on trailing earnings is now 19.1, compared with 29.7 in late 1999 when the Nasdaq first reached 4,000, he points out. The cyclically adjusted P/E ratio, or Shiller P/E, is 24.4, compared with 44.2 in 1999. The price-to-book ratio is 2.6 versus 5.1, and the price-to-sales ratio is 1.6 versus 2.4.

"So, please, let's stop the comparisons to the Internet bubble," he urges.

Editor’s Note: 5 Reasons Stocks Will Collapse . . .

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