This paper uses three models to estimate the financial performance of 33 securities traded on the Athens Stock Exchange (ASE). To estimate the expected returns, this study uses the Capital Asset Pricing Model (CAPM), the Market Model, and the Arbitrage Pricing Theory (APT). There is significant evidence that the APT performs better than the CAPM and the Market Model, while the differences between the CAPM and the Market Model appear not to be significant. The three models are tested for a five-year period from 2000 to 2005. Total risk is significantly negatively related to returns during down markets, while this relationship is positive but not significant in up markets. There is evidence that, apart from the market risk, other risk factors that influence the stock returns are the inflation rate and the exchange rate.