The price of stock in social-media giant Facebook is plunging on its second day of trading.

In the first hour on the Nasdaq exchange Monday, traders quickly started selling the stock with its price falling more than 11 percent to below $34.

Facebook shares had edged slightly higher on the stock's opening Friday, ending up 23 cents from the initial offering at $38.

With more than 900-million users, the social networking site is a well-known product. But some financial analysts say they think the company is overvalued, with projections for its advertising revenue falling.

The Nasdaq exchange said Sunday it mishandled the opening of trading in the stock on Friday, with technology problems preventing some large and small investors from completing their stock trades. Some investors say they lost money because of the glitches. Nasdaq says it is recreating the trades that were made to determine which stock buyers and sellers are owed compensation.