A Columbia Business School professor and mentor of Warren Buffett. Graham is the so called “father of value investing”. He wrote the best selling books Security Analysis and The Intelligent Investor in which he explains the value investing framework in detail.
Graham pointed out that stock prices often divert significantly from the actual fundamental value of the underlying business. He believed that buying stocks of solid businesses when they are under-priced with respect to their fundamental value allows someone to make a good return on investment at a lower risk. This rational analysis method was quite different from the speculative "greater fool" mentality that seemed to dominate Wall Street.