A sign displays the Twitter logo on the front of the New York Stock Exchange ahead of the company's IPO in New York, November 7, 2013. [Photo/Agencies]

NEW YORK - Twitter Inc shares jumped 73 percent in a frenzied trading debut that drove the seven-year-old company's market value to around $25 billion and evoked the heady days of the dot-com bubble.

The strong performance on Thursday is encouraging for the venture capitalists who have backed other consumer Web startups, such as Square or Pinterest, though it sounded alarm bells for some investors who cautioned that the froth was unwarranted.

"@twitter opening at $45/share? Almost 50x revenues! We are officially in another tech bubble," tweeted financier and investment advisor Steve Rattner.

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 Inc's $16 billion IPO last year and ahead of Google Inc's

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.

"When people use Twitter they are following certain people, they're searching for specific information," said Mark Mahaney, an analyst at RBC Capital Markets. "There are powerful marketing signals that are almost Google-esque, something that Facebook doesn't really have."

The IPO was shadowed for months by Facebook's troubled 2012 debut, in which the shares quickly fell below their offering price amid trading glitches and subjected the company and its lead banker, Morgan Stanley, to accusations that they had been greedy in pricing the deal.

Twitter's opening appeared to go off without a hitch, prompting Anthony Noto, the Goldman Sachs banker who led the IPO, to write a simple Tweet: "Phew!"

Still, Twitter may find itself subject to the opposite criticism, that it had priced the shares too low and left more than a billion dollars on the table.

"In my mind they certainly could've raised the price on this thing and gone into the low 30s," said Ken Polcari, director of the NYSE floor division at O'Neil Securities. "From an outsider looking in I would say they were overly cautious because they didn't want a disaster on their hands ... I'm sure the company didn't want a Facebook debacle, I get that, but I think they were overly cautious and it cost them some money."

The 70 million IPO shares represent about 13 percent of the company's common shares. Twitter was the most actively traded stock on Thursday, with around 117 million shares changing hands.

Heavy demand for the IPO was apparent before the final pricing. Twitter was able to price the IPO above an already raised indicative range, and the deal still attracted investor subscriptions that totaled 30 times the number of shares on offer, according to market sources.