In recent years, the financial service industry demonstrated substantial growth of Exchange Traded Funds (ETFs). Apart from offering access to new and more specific investment opportunities, many ETFs enter direct competition with conventional, already existing Mutual Index Funds. With 22,1% growth of assets over the past 5 years, the European market by now accounts for 19% of the global ETF market, while at the same time we observe a decline of cash flows to Mutual Index Funds. Given the recent development, index investors are likely to face a choice between ETFs and Mutual Index Funds offering the same service. The purpose of this study is to analyze those two similar investment instruments towards the quality of achieving their objective, which is to deliver a performance as close as possible to the respective benchmarks'. The analysis will be performed for the European market, i.e. we include only Index Funds that track European indices.