American multinational holding company, Berkshire Hathaway owns GEICO, Dairy Queen, Helzberg Diamonds and Duracell, as well as many other companies. It has a long, rich history of smart investments, which propelled it to the number five position in the world in terms of market capitalization. 

Berkshire has tight controls over its interns and qualifications are stiff. However, those who are selected will have tremendous insight into the investing world.