Purpose – The purpose of this paper is to examine the relationship between the Athens Olympic Games and the Athens Stock Exchange (ASE). It aims to test: the effect of the Athens 2004 Olympics on the general index of the ASE; the impact of the Olympic Games 2004 to the sponsors’ prices traded on the ASE (based on three National sponsors and one International sponsor); and the effect of the Greek Olympic Champions (winners’ effect) on the course of the ASE. Design/methodology/approach – This paper captures financial time series characteristics by employing an AR(1)-GARCH(1,1) model with generalized error distribution (GED). The paper uses daily closing prices for the General ASE index and four Grand Sponsors listed in the ASE (Coca-Cola, Alpha Bank, OTE, and Cosmote) over the period 19 January 1996 to 20 December 2005. Findings – The results show no effect on the general ASE index, but a positive effect on the OTE (Hellenic Telecommunications Organisation) index. Also, the results show a positive effect of Greek Medallists on the ASE index and two National sponsors, Alpha Bank and OTE. Research limitations/implications – Further research should investigate the impact of other mega sporting events (Mundial, European Championships) on the course of international stock markets using high-frequency datasets and models. Practical implications – The findings are strongly recommended to financial managers and investors dealing with Greek stock indices. Originality/value – The contribution of this paper is to examine the above hypotheses on the relationship between the Athens Olympic Games and the ASE using a large sample data, and a Generalised Autoregressive Conditional Heteroskedasticity (GARCH) model with GED.