SUNNYVALE, Calif., Nov. 29 (UPI) -- Billionaire investor Carl Ichan has upped his ownership stake in U. S. Internet technology company Yahoo Inc., buying 6.8 million shares, documents show.

U. S. Securities Exchange Commission documents revealed Ichan, a board member of the Sunnyvale, Calif., Web search engine and Internet portal, spent approximately $67 million to purchase the shares at $9.88 each, increasing his ownership stake to just under 5 percent of Yahoo's outstanding shares, The Wall Street Journal reported Saturday.

Analysts said Ichan's buy marks the first time he has significantly expanded his stake in Yahoo Inc. since joining its board as part of his proxy fight for control of the company. Sources told the Journal that Icahn believes Yahoo's stock is undervalued and is hoping that a stalled Web search deal with Microsoft Corp. may eventually be done.

Other Yahoo board members are concentrating on the search to replace departed chief executive Jerry Yang, and have begun interviewing potential candidates, including the leaders of some non-Internet technology companies, sources told the newspaper.