Sunnyvale-based Yahoo has been offered $44.6B in cash and stock by Microsoft for the firm, in a deal announced this morning. Microsoft said that it is proposing to offer shareholders of Microsoft stock either cash or stock for Yahoo, in a deal worth $31 per share. The offer is a 62 percent premium over Yahoo's closing stock price on Thursday. Microsoft said it hopes to generate synergies worth at least $1B a year by combining the companies, and that it will offer significant retention packages to Yahoo! employees. If accepted by Yahoo! shareholders and the board, Microsoft hopes to complete the buyout of Yahoo in the second half of the year.