Yahoo founder Jerry Yang has come out as another potential buyer for the company, adding to a list of interested parties that includes Silver Lake and Alibaba, venture capitalists Andreessen Horowitz and -- for the third time in three years -- Microsoft. According to Reuters, Yang’s bid involves a deal between private equity firms under which he would rollover his 3.6 percent stake in the company and might see co-founder David Filo add his his 5.9 percent stake into the mix. If successful, the floundering search engine / Web portal, which is valued at approximately $20 billion, would once again be a private company. At this stage, any talks between Yang and potential backers are said to have been informal. That may change this week as financial information begins to emerge. On Friday, Yahoo shares were trading for $15.47, a far cry from the $31 - $33 range that Microsoft offered back in August 2008, and a good deal less than Yang’s $37 per share counter offer.