In 1941, when Warren was 11 years old, he bought his first stock—three shares of Cities Service. He had been interested in business and investment from a very early age, inspired by a book he borrowed from the library at the age of seven: ‘One Thousand Ways to Make $1000.’

Before turning 11, he tried several businesses such as selling chewing gum and Coca-Cola, delivering magazines, working in grocery stores, delivering newspapers, selling golf balls and stamps, and detailing cars, among others.