Twitter is a real-time online social networking platform founded in 2006. As of 2012 it reported over 500 million active users generating over 340 million tweets daily, making it one of the world's most visited websites. 

Twitter shares dropped 3.7 per cent on Wednesday to US$30.66 at the close in New York. Photo: Reuters

Twitter declines after sales lock on shares ends

Twitter shares fell to the lowest level since the company's initial public offering, following the lifting of restrictions on stock sales by insiders and early investors.