Twitter announces, via tweet, that it has filed for an IPO

Twitter has filed for an initial public offering of stock, months earlier than expected.

The 7-year-old microblogging site announced the news -- via tweet, of course -- on Thursday afternoon: “We’ve confidentially submitted an S-1 to the SEC for a planned IPO. This Tweet does not constitute an offer of any securities for sale.”

A minute later, Twitter followed up its IPO tweet with a new message: “Now, back to work” along with a photo of employees in the company’s San Francisco offices.

Twitter’s valuation has been estimated at about $10 billion.

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Under new federal rules, a confidential filing is permitted if a company brings in less than $1 billion in annual revenue.

Thursday’s news came as a bit of a surprise, as many tech watchers and analysts hadn’t expected the company to file until early 2014 at the earliest.

Research firm EMarketer estimates that Twitter will generate $583 million in advertising sales this year. It’s not forecast to cross the $1-billion threshold until 2015, when EMarketer expects Twitter to rake in $1.3 billion in ad revenue.

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But more than half of Twitter’s revenue already comes from mobile advertising, eliminating one of the main concerns that investors had about Facebook at the time of its IPO.

A Twitter spokesman declined to comment.

Josef Schuster, founder IPO research and investment house IPOX Schuster in Chicago, said now, especially, “is a good time to go public.”

“The stock market is doing remarkably well, the economy is good, plenty of capital is available. The stock market is trading at an all time-high,” he said. “It’s been a very good year for IPO investors.”

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