Essay from the year 2014 in the subject Business economics - Investment and Finance, grade: 16,0, University of St Andrews (School of Management), course: Research Methods in Finance and Management, language: English, abstract: The size effect is a market anomaly in asset pricing according to the market efficiency theory. According to the current body of research, market anomalies arise either because of inefficiencies in the market or the underlying pricing model must be flawed. Anomalies in the financial markets are typically discovered form empirical tests. These tests usually rely jointly on one null hypothesis H0= markets are efficient AND they perform according to a specified equilibrium model (usually CAPM). Thus, if the empirical study rejects the H0, the reason could either be due to market inefficiency or due to the incorrect model. Market efficiency theory says that the price of an asset fully reflects all current information and is not predictable (Fama 1970). Fama (1997) states that market anomalies, even long--term anomalies, are not an indicator for market inefficiencies due to the reason that they randomly split between "underreaction and overreaction, (so) they are consistent with market efficiency" (p. 284), they happen by chance and it is always possible to beat the market by chance. This essay will give an overview of the literature of the size effect and will stress the key theories, empirical methods and findings, as well as the existing body of research about this particular anomaly.