A post on Microsoft's blog from Senior Attorney, Microsoft Digital Crimes Unit Richard Boscovich has offered a $250,000 reward for information regarding the creators and operators of the Rustock botnet. Reuters

Microsoft (Nasdaq: MSFT), the world's biggest software company, is in seeking to divest its remaining investment in, the No. 4 U.S. news website.

The software giant, which previously announced it expects to report a $6.3 billion fourth-quarter loss due to goodwill writedowns in its Internet Services Division, established the site with NBCUniversal, then a unit of General Electric Co. (NYSE: GE), in 1997.

The Redmond, Wash.-based Microsoft also was a founding 50 percent partner of the MSNBC cable channel, in which it invested $220 million. It sold a 32 percent interest back to NBC in 2005 and the remainder in 2007.

A representative for Comcast Inc. (Nasdaq: CMCSA), the No. I cable company that acquired NBCUniversal in 2010, confirmed discussions are taking place but had no further comment.

Microsoft, which reported nearly $60 billion in cash and investments last quarter, has spent heavily to develop its Windows 8 OS, scheduled for shipment this quarter. But it's also built up its own Bing website into the No. 2 search engine, as well as forged a technical partnership with No. 3, Yahoo (Nasdaq: YHOO).

Market researcher comScore (Nasdaq: SCOR) estimated Bing's share of search had risen to 15.6 percent in June, compared with 14.4 percent a year ago. Yahoo's share fell to 13 percent.

Nielsen (Nasdaq: NLSN), another market research company, ranked as the No. 4 U.S. news website, while the Yahoo-ABC News co-branded site was No. 1.

Many media executives are currently meeting in Sun Valley, Ida., for the annual investment forum organized by Allen & Co., the Wall Street media firm that is currently advising Yahoo on strategy and was an underwriter of the $16 billion initial public offering of Facebook (Nasdaq: FB), the No. 1 social networking site, on May 17.

Shares of Microsoft fell 67 cents to $28.63 on Thursday, while those of Comcast fell 63 cents to $31.10.