Facebook shares drop below flotation price
On its second day of trading as a public company Facebook's share price has dropped sharply.
When the shares first went on sale last Friday the company was valued at over $100bn (more than £60bn).
Despite the wider market in a buoyant mood, Facebook slid 12% immediately at the opening bell the following Monday.
The BBC's Technology Correspondent Rory Cellan-Jones explains what that means for the company.