Investors are quickly losing interest in the world's most popular social network, which went public last Friday.

While many expected Facebook (NASDAQ: FB) shares to fly high -- maybe not on the level of LinkedIn (NASDAQ: LNKD), but certainly on par with other major IPOs -- the company ended its launch with minimal gains.

Now the stock is tanking, trading down as much as 12% today.

"Facebook has not answered many key issues facing Facebook business," Trip Chowdhry, the Managing Director of Equity Research at Global Equities Research, wrote in an e-mail update on the stock. "We think [that] until and unless Facebook management answers [our] questions, investors may not be comfortable with the Facebook valuations."