A woman uses an iPad with a Facebook app in this photo illustration in Sofia January 30, 2013. Facebook Inc’s advertising business grew at its fastest clip since before the company’s May initial public offering, helping the company’s revenue expand 40 percent to $1.585 billion. Shares of Facebook were down 2.5 percent to $30.45 in after hours trading on Wednesday. REUTERS/Stoyan Nenov (BULGARIA – Tags: BUSINESS)