Value investing is an investment paradigm that derives from the ideas on investment and speculation that Ben Graham & David Dodd began teaching at Columbia Business School in 1928 and subsequently developed in their 1934 text Security Analysis. Although value investing has taken many forms since its inception, it generally involves buying securities whose shares appear underpriced by some form(s) of fundamental analysis.[1] As examples, such securities may be stock in public companies that trade at discounts to book value or tangible book value, have high dividend yields, have low price-to-earning multiples or have low price-to-book ratios.

High-profile proponents of value investing, including Berkshire Hathaway chairman Warren Buffett, have argued that the essence of value investing is buying stocks at less than their intrinsic value.

The discount of the market price to the intrinsic value is what Benjamin Graham called the "margin of safety". The intrinsic value is the discounted value of all future distributions.

However, the future distributions and the appropriate discount rate can only be assumptions. Warren Buffett has taken the value investing concept even further as his thinking has evolved to where for the last 25 years or so his focus has been on "finding an outstanding company at a sensible price" rather than generic companies at a bargain price.

Performance, value strategies
Value investing has proven to be a successful investment strategy. There are several ways to evaluate its success. One way is to examine the performance of simple value strategies, such as buying low PE ratio stocks, low price-to-cash-flow ratio stocks, or low price-to-book ratio stocks. Numerous academics have published studies investigating the effects of buying value stocks. These studies have consistently found that value stocks outperform growth stocks and the market as a whole.

Performance, value investors
Another way to examine the performance of value investing strategies is to examine the investing performance of well-known value investors. Simply examining the performance of the best known value investors would not be instructive, because investors do not become well known unless they are successful. This introduces a selection bias. A better way to investigate the performance of a group of value investors was suggested by Warren Buffett, in his May 17, 1984 speech that was published as The Superinvestors of Graham-and-Doddsville. In this speech, Buffett examined the performance of those investors who worked at Graham-Newman Corporation and were thus most influenced by Benjamin Graham. Buffett's conclusion is identical to that of the academic research on simple value investing strategies--value investing is, on average, successful in the long run.
During about a 25-year period (1965-90), published research and articles in leading journals of the value ilk were few. Warren Buffett once commented, "You couldn't advance in a finance department in this country unless you taught that the world was flat."