And investment mogul Warren Buffet has announced what is believed to be the largest charitable donation in U.S. history. Buffet says he will give 85% of his estimated $44 billion fortune. $31 billion will go to the Gates foundation — the charity run by Microsoft founder Bill Gates and his wife Melinda. However, there is uncertainty over whether the donation will reach the announced total. The money will be given to the Gates Foundation in small annual sums, and will require the active involvement of at least one of the Gateses in order to continue.