»Financial Market Risks Due to ETFs and Closet Indexing. An Empirical Analysis of the German Stock Market«: The thesis is a contribution to a fundamental discussion in capital market research, the measurable success of »active vs. passive« investment strategies. The author critically examines the principal investment strategies and models for index products and, at the same time, sheds light on closet indexing in actively managed mutual funds. The result shows that closet indexing does not only occur sporadically but is an overall investment strategy in many supposedly actively managed equity funds.