Facebook shares were sold to the public at $38 apiece in a deal that valued the company at $104bn, but the group rapidly tumbled following its trading debut on May 18 last year, eventually reaching a record low of $17.729 in September. Since then, the shares have rallied but last night’s close of $26.13 is still 31pc below the original flotation value. That gives Facebook a market capitalisation of $63.1bn, significantly below its value at IPO.