Gates studied the work of Andrew Carnegie and John D. Rockefeller, and in 1994 sold some of his Microsoft stock to create the "William H. Gates Foundation." In 2000, Gates and his wife combined three family foundations to create the charitable "Bill & Melinda Gates Foundation," which was identified by the Funds for NGOs company in 2013 as the world's wealthiest charitable foundation, with assets reportedly valued at more than US$34.6 billion.[94][95] The Foundation allows benefactors to access information that shows how its money is being spent, unlike other major charitable organizations such as the Wellcome Trust.[96][97]