According to Bloomberg, the stock had fallen 7.4 percent to $29.55 by midday in New York, well below the offer price of $38 a share.
“People are disillusioned,” Matt McCormick of Bahl & Gaynor Inc. in Cincinnati told Bloomberg.
“A lot of investors believed the hype. In this type of volatile market environment, people are not going to take chances.”
The Wall Street Journal said the beginning of options trading and negative sentiment around the stock weighed on Facebook’s share price.
Another issue dragging the stock lower was speculation that Facebook was considering a takeover of Opera Web browser in Norway, Mercury News reported.
Shares in Facebook have lost nearly a quarter of their value since the May 18 IPO, which valued the company at more than $100 billion, the BBC reported.
Facebook is under pressure for a number of reasons.
Investors are worried that the social networking site is overvalued and want to know how it plans to profit from its more than 900 million users.
Regulators, meanwhile, are investigating allegations that the company concealed critical information ahead of its IPO, the Guardian reported.
And shareholders have launched legal action against the founder Mark Zuckerberg, the company and its bankers for failing to disclose "a severe and pronounced reduction" in forecasts for Facebook's revenue growth.