In a regulatory filing late Thursday, Twitter set a preliminary price range of $17 to $20 per share for its IPO. It also raised the maximum size of its offering to $1.4 billion, up from its previous $1 billion.

The company has about 545 million shares outstanding, so Twitter would be valued as high as $10.9 billion -- slightly above previously reported valuation estimates.

Twitter plans to sell about 70 million of its shares in the IPO.

The company's target price range isn't binding, so we don't yet know what price Twitter will ultimately set for its IPO. The company will file several more rounds of paperwork before the IPO to provide a variety of new details -- anything from setting a new price range, to more information about items like executive compensation.

Twitter will have to set its final price the night before it begins trading, but that won't be for another few weeks.