Last week, Microsoft made an unsolicited offer to buy Yahoo! It looks like Yahoo! is about to reject that offer, telling them that they've undervalued the company.

Yahoo! will reportedly state their reasons for rejecting the Microsoft offer on Monday. Those reasons could include partnership deals with other companies, like Google, or antitrust concerns. They may also just be holding out for a better price.

• Microsoft Offers to Buy Yahoo!
• Google Responds to Microsoft