XO Holdings Inc Chairman and billionaire investor Carl Icahn on Friday offered to buy the shares in the communications company that he does not already own for 55 cents each.

Icahn's affiliate ACF Industries Holdings Corp already owns 52.68 percent of XO, which provides communications services to businesses and other service providers, according to filings with the U.S. Securities and Exchange Commission.

On July 9, ACF Industries submitted an offer to buy the rest of XO for 55 cents a share, which marked a 100 percent premium over the stock's closing price on Thursday, according to an SEC filing.

The offer was not subject to financing commitments or due diligence, the filing said.

Shares of XO jumped 21 cents or 75 percent to 49 cents in Bulletin Board trading on Friday.

XO could not be immediately reached for comment.

In addition to serving on the board of XO, Icahn serves on the boards of several other companies, including Yahoo Inc, American Railcar Industries Inc, WCI Communities Inc and Blockbuster Inc. He also is chairman of his Icahn Enterprises holding company.

(Reporting by Jessica Hall, editing by Gerald E. McCormick)