Carhart four-factor model

In portfolio management, the Carhart four-factor model is an extra factor addition in the Fama–French three-factor model, proposed by Mark Carhart. The Fama-French model, developed in the 1990s, argued most stock market returns are explained by three factors: market beta (stocks more volatile than the broad market tending to outperform), price (value stocks tending to outperform) and company size (smaller company stocks tending to outperform).

Source: Wikipedia — Carhart four-factor model (CC BY-SA 4.0)