Value investing is an investment paradigm that involves buying securities that appear underpriced by some form of fundamental analysis. Modern value investing derives from the investment philosophy taught by Benjamin Graham and David Dodd at Columbia Business School starting in 1928 and subsequently developed in their 1934 text Security Analysis.

The early value opportunities identified by Graham and Dodd included stock in public companies trading at discounts to book value or tangible book value, those with high dividend yields and those having low price-to-earning multiples or low price-to-book ratios.

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". Buffett further expanded the value investing concept with a focus on "finding an outstanding company at a sensible price" rather than generic companies at a bargain price. Hedge fund manager Seth Klarman has described value investing as rooted in a rejection of the efficient-market hypothesis (EMH). While the EMH proposes that securities are accurately priced based on all available data, value investing proposes that some equities are not accurately priced.

Graham himself did not use the phrase value investing. The term was coined later to help describe his ideas. The term has also led to misinterpretation of his principles - most notably the notion that Graham simply recommended cheap stocks.

The concept of intrinsic value for equities was recognized as early as the 1600s, as was the idea that paying substantially above intrinsic value was likely to be a poor long-term investment. Daniel Defoe observed in the 1690s how stock for the East India Company was trading at what he believed was an elevated price of over 300% more than face value, "without any material difference in Intrinsick [sic] value."

Hetty Green (1834-1916) was retrospectively described as "America's first value investor." She had a habit of buying unwanted assets at low prices, which she held, as she stated in 1905, "until they go up [in price] and people are anxious to buy."

The investing firm Tweedy, Browne was founded in 1920 and has been described as "the oldest value investing firm on Wall Street". Founder Forest Berwind "Bill" Tweedy initially focused on shares of smaller companies, often family owned, which traded in lower numbers and lower volume than stock for larger companies. This niche allowed Tweedy to buy stocks at a significant discount to estimated book value due to the limited options for sellers. Tweedy and Benjamin Graham eventually became friends and worked out of the same New York City office building at 52 broadway.

Economist John Maynard Keynes is also recognized as an early value investor. While managing the endowment of King's College, Cambridge starting in the 1920s, Keynes first attempted a stock trading strategy based on market timing. When this method was unsuccessful, he turned to a strategy similar to value investing. In 2017, Joel Tillinghast of Fidelity Investments wrote: