The most hotly anticipated IPO of the year did not disappoint overnight when shares of Twitter spiked nearly 75% above the opening price of US$26 dollars at the opening bell on Wall Street.  

The micro-blogging service went public on the New York Stock Exchange with Twitter experiencing a 73% jump on its trading debut. The stock rose to US$44.90 at the close in New York from the initial public offering price of US$26

Based on today's trading, it's been reported co-founder Evan Williams' stock would be worth US$2.9 billion, while fellow co-founder Jack Dorsey's stock would be worth US$1.2 billion.

The seven-year-old online social media service is now valued at more than US$30 billion. 

Despite the impressive showing, doubts persist about how profitable the company will be.