Microsoft has signed an agreement that will allow it to take a look at Yahoo! Inc.'s financial documents to help them in their bid for the company. 3 years ago they failed to buy Yahoo! for $45 billion and take control of the company. The goal of that purchase was to create a competitor to go against Google.
Yahoo! has said that their advisors want bids to be submitted by next week. These bidders are most likely to offer to buy only a minority stake in Yahoo! rather than go for a full takeover of the company. Microsoft along with other investors would all pitch in on this upcoming bid.
Recently Microsoft joined Yahoo! in a 10 year agreement to provide search functionality for Yahoo! where their Bing search engine gets answers to user queries and Yahoo! sells ads against those results. The agreement was aimed at helping both companies compete with Google. The Yahoo of today is in a weaker position than it was in 2008.