the last century. em ... no ... the Gates foundation mainly invests in medical research and education, that means donating now adds a tremendous value compared to donating in ten years. Because the 10.000.000 people dying from malaria will otherwise be dead. i.e. He's not giving 85% away, he's giving a number of shares each year that decrease in number at the rate of 5% a year (until gone?). He mentions his wife's death having an effect on him. It sounds pretty rational that he's saying that Bill and Melinda are at a prime spot, so starting the money hose now is a good idea, but Buffet is still keeping most of his donation inside of Berkshire where it will compound. Bill over at The Fourth Rail has