Men are silhouetted against a video screen with an Twitter logo as he poses with an Samsung S4 smartphone in this photo illustration taken in the central Bosnian town of Zenica, August 14, 2013. [Photo / Agencies]

Twitter Inc has filed for an initial public offering with US regulators, the company said on Thursday, taking the first step toward what would be Silicon Valley's most anticipated debut since Facebook Inc's last year.

The impending IPO of the microblogging phenomenon ignited a competition among Wall Street's biggest names for the prestige of managing its coming-out party. Goldman Sachs is lead underwriter, a source familiar with the matter said on Thursday, which is a major coup for the Wall Street bank.

Twitter filed for an IPO confidentially under a 2012 law intended to help emerging corporations with less than $1 billion in revenue go public.

Seven-year old Twitter, which allows users to send out streams of 140-character messages, has become an indispensable tool to governments, corporations and celebrities seeking to communicate with their audience, and for individuals seeking both news and entertainment.

Chief Executive Dick Costolo has for years waved off suggestions it intended to go public, saying the company remained flush with cash. Facebook's mismanaged 2012 debut and subsequent share-price plunge also chilled the consumer-dotcom IPO market.

Facebook, however, has clawed its way back to its $38 IPO price in July, and the stock is at a record high after touching $45 this week.

Twitter, which has been valued by private investors at more than $10 billion, should break even this year and is on track for 40 percent annual growth at a $1 billion annual revenue run rate, Max Wolff of Greencrest Capital estimated.

"It's completely conquered mobile. It has an enormous social network. It's becoming a key utility as a second screen to TV and it's literally the first draft of history," Wolff said.

"Normally a company like Twitter would have been public for some time," he said.

Since Jack Dorsey, Twitter's inventor, dispatched the first tweet from a downtown San Francisco office in March 2006, the service has grown into a worldwide phenomenon with more than 200 million regular users contributing more than 400 million posts a day.

The company makes money by inserting paid, targeted ads that resemble ordinary, user-generated content. Twitter's success with its advertising model created a new paradigm for mobile advertising and prompted Facebook last year to adopt a similar ad product, called Sponsored Stories.

But Twitter was one of the first to prove that in-stream ads could be a viable way to make money in the mobile era.

"There was a lot of concern about whether they'd ever be able to insert advertising into their site," said Forrester analyst Nate Elliott. "They've shown it can be effective. They offer in many ways better measurement for marketers than larger companies like Facebook."

Twitter's lead law firm will be Wilson Sonsini Goodrich & Rosati, the firm's chairman Larry Sonsini told Reuters in an email. Sonsini's firm is famous in Silicon Valley for taking public marquee names such as Apple , Netscape and Google .

Jostling for roles

Technology bankers at major banks from JPMorgan and Credit Suisse Group AG to Morgan Stanley are still vying for roles in the IPO. Several are in informal conversations with the microblogging network's management, said two sources familiar with the matter who declined to be named because it is not public.