The Facebook stock fell nearly $5 to $33.64/67 a share on Monday from its Friday closing price of $38.23 a share, denting CEO Mark Zuckerberg's fortune by nearly $2bn (£1.3bn) to $18.7bn.
The Facebook stock, which plunged as far as 13.7 per cent from its Friday's closing price of $38.23, also shaved around $4 billion off the social networking site's record initial valuation of $104 billion.
The stock of the Menlo Park company, trading without underwriter's support, was already down nearly 4 per cent at 36.80 when markets opened, a decrease of 3.8 per cent from Friday's close.
Shares opened at $36.53 and dropped to below $36 in the first 30 minutes of trading. The stock hit a low of $33, down 13.7 per cent from Friday's closing price. The stock later pared some losses and the was trading at $33.64/67, down 12 per cent from Friday's close.
At $33.64/67, the Facebook stock is close to 24.4 per cent down from its Friday's intraday high of $45 a share.
The stock plunge also left an over $2 billion dent in Facebook CEO Marck Zukerberg's personal wealth as well.
Trading volume was high at over 52 million shares changing hands in 15 minutes against Friday's total of nearly 581 million shares traded on Friday in the five hours that the stock was open.
The Facebook IPO, lead-underwritten by Morgan Stanley, listed on the Nasdaq with huge enthusiasm and was the most heavily traded IPO of all time.