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“My cut of the pie goes down,” Mr. McWilliams said.

The Washington University study, “A Persistent Anomaly,” found that tech stocks had what the scholars called a high “beta” score, meaning that they are perceived to be riskier and thus tend to lose the most value after the lockup period expires.

Facebook probably will be a high beta stock,” said Jonathan Woo, a graduate student who worked on the study, along with Sam Poteat and Borge Klungerbo. “Tech stocks generally have higher betas.”

The negative effects of the lockup are usually felt in the three to five days after the expiration, Ms. Damiani said. She suggests that the true value of the stock will begin to show itself about 60 days later, by which time investors have a chance to see the company’s earnings report and make a rational decision on whether to invest.

At this point, Ms. Damiani said, Facebook stock could drop near its original trading price in the $50s. Mr. McWilliams said it could drop even further to the $40s.

But Facebook poses another problem investors must consider - that the social network could become outdated if either Facebook users flock to another site or social networking becomes generally unpopular.

“We are afraid that it is coming to a phase where it could be another MySpace,” Ms. Damiani said. “It has a lot of contenders in the shadows.”

Not all tech stocks have folded. While social media stocks struggle because of the ever-changing nature of the industry, companies in other tech sectors are having much success.

Apple, known for popular devices like the iPhone and iPad, is distinguishing itself as the wealthiest company in the world. This week, it topped $500 billion in value, becoming one of only five companies in history to do that. It is trading at about $545 a share, up from about $10 a decade ago.

Google, which went public in 2004, opened at $85 a share, but is now trading about $620. The Internet giant is worth more than $200 billion.