After his unusually enthusiastic declaration at a Silicon Valley event last week that “we are very, very interested” in buying the “whole” of Yahoo, you might imagine Alibaba Group co-founder and CEO Jack Ma running out of the speech looking for a giant pile of cash to pay for it immediately. Instead, according to sources close to the situation, what the Chinese entrepreneur got was a cold dose of CFIUS – or Committee on Foreign Investment in the United States, the federal interagency review process for foreign investment deals.