By Olivia Oran and Gerry Shih NEW YORK/SAN FRANCISCO (Reuters) – Twitter Inc shares jumped 73 percent in a frenzied trading debut that drove the seven-year-old companys market value to around $25 billion and evoked the heady days of the dot-com bubble. The stock closed its first day of trade on the New York Stock Exchange at $44.90 a share after hitting a session-high of $50, nearly double the initial public offering price of $26 set late on Wednesday. Twitter could raise $2.1 billion if an underwriters over-allotment is exercised, as expected, making it the second largest Internet offering in the United States behind Facebook Incs $16 billion IPO last year and ahead of Google Incs 2004 IPO, according to Thomson Reuters data. Fans believe that Twitter, which has 230 million users, has established itself as an indispensable Internet utility alongside Google and Facebook, and that it has only scratched the surface of its potential as a global advertising medium.