Facebook warns of app threat to profits

Jan-Philipp Strobel/DPA/Press Association Images

Just one week before Facebook floats on the stock exchange it has taken the unusual step of releasing bad news to the market. It said that the proportion of users accessing Facebook on their smartphone and tablet has shot up, and taken it by surprise. The relatively undeveloped advertising proposition on these gadgets is expected to mean advertising revenues are not going to be as high as expected.

So why has Facebook released this information, and what will it mean?