Nearly half of Americans believe that popular social-networking site Facebook is merely a passing fad, a new study suggests.

A poll conducted by the Associated Press and CNBC found that 46% of respondents think Facebook will fade away as new platforms come along in the future. However, about 43% believe the site will likely be successful for the long haul.

The study was conducted among 1,000 Americans ages 18 and over, with a margin of error of 3.9%.

The survey comes as Facebook readies for its initial public offering later this week. The company confirmed on Tuesday that shares will be priced between $34 and $38, with the company's valuation at more than $100 billion.

About 50% of respondents said they believe the expected stock market value is overvalued, while only 3% said the projection is undervalued. About 32% said that the number is valued fairly by the market. The remaining percentage either didn't know or declined to answer.

The study also asked respondents if buying Facebook shares would be a good investment that would outperform other investments — about 51% believed it would be a good investment, while 31% disagreed.

As for whether or not people believe 28-year-old Facebook CEO Mark Zuckerberg can run a large publicly traded company, only 18% said they were extremely confident. About 40% said they were somewhat confident and 20% said they weren't confident at all. Respondents cited age as helping his ability to run the company (21%) compared to hurting his ability (11%).

Do you think Facebook is just a passing fad? Let us know your opinion in the comments.

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