Types of Businesses: which makes sense?

I am a writer and I have little to no business knowledge. I need to know what type of business best fits the character I have in mind. He is EXTREMELY wealthy, owns his business and runs it, though he has underlings that help him, but he himself is not liable for legal issues involving his company. The nature of his company is finance, loaning to not only to individuals but also to companies or other businesses, sometimes even the government. Keep in mind this is a FICTION story and so doesn't have to be 100% legally accurate, though any information that doesn't fit I would also like to know. This type of business should be believable as a fictitious Fortune 500-like business, the kind of business that a great many people have heard about or know. What I need is to know any information you think may be helpful, and wether or not it is a cooperation, a limited liability company, or anything else it could be. Thank you.