But the documents are sealed, as Twitter is taking advantage of federal legislation passed last year that allows companies with less than $1 billion in revenue in its last fiscal year to avoid submitting public IPO documents.
San Francisco-based Twitter Inc. posted on its official Twitter account Thursday afternoon that it has "confidentially submitted an S-1 to the SEC for a planned IPO."
The confidentiality will likely help Twitter avoid the public hoopla that surrounded the initial public offerings of other high-profile social networking companies, including Facebook Inc., which went public in May 2012.
Twitter's IPO has been long expected. The company has been ramping up its advertising products and working to boost ad revenue in preparation.