Value investing was developed by Columbia Business School professor Benjamin Graham — Warren Buffett's mentor — in the 1930s and was popularized in his 1949 book, The Intelligent Investor https://www.grahamvalue.com/article/how-build-complete-benjamin-graham-portfolio In a 2008 foreword for Graham's earlier book — Security Analysis — Buffett wrote: "Graham laid out a roadmap for investing that I have now been following for 57 years. There’s been no reason to look for another." In a 2018 interview for Bloomberg Markets, Buffett once again said: "Investing principles haven't changed at all. It's exactly what Ben Graham wrote in 1949." Sources: Warren Buffett: Benjamin Graham's Principles Still Valid In 2018 https://www.youtube.com/watch?v=1dBOOgXxebM Warren Buffett: No other framework as successful as that of Benjamin Graham https://www.youtube.com/watch?v=s9HGDFkN3KA Warren Buffett: Owe Fisher and Munger a lot, but Benjamin Graham was one of a kind https://www.youtube.com/watch?v=sBtyt-rafKg Warren Buffett: Would Hire Someone Who Understands Graham Over Top B-School Grad https://www.youtube.com/watch?v=NcT8o2kT_WE More sources:    • Why Benjamin Graham?   Transcript: Warren Buffett is considered one of the most successful investors in the world today, with a net worth of over $100 billion. At age 19, after reading through every book the Omaha Public Library had on investing, Buffett finally found “The Intelligent Investor” by Benjamin Graham. In a later 1986 preface to the same book, Buffett would write that "Graham influenced my life more than any other man except my father". Buffett studied under Graham at Columbia Business School, and then went on to work at the Graham-Newman Corp. Buffett would eventually even name his son after Graham. Graham's framework is timeless because it accounts for inflation rates, and includes instructions to compensate for prevailing interest rates. For regular investors, Graham recommended three categories of stocks — Defensive, Enterprising, and Net-Net — with seventeen rules for growth, stability, earnings and assets. For professional investors, Graham described various "special situations" which required long experience and exceptional judgment. The latter followed no specific rules, but the seventeen rules for regular investors were completely quantitative in nature. The statistical work of identifying such stocks is easily automated using modern data mining software. In a 2008 foreword for Graham's earlier book — Security Analysis — Buffett wrote: "Graham laid out a roadmap for investing that I have now been following for 57 years." In a 2018 interview for Bloomberg Markets, Buffett once again said: "Investing principles haven't changed at all. It's exactly what Ben Graham wrote in 1949."