The appointment of capable top executives is an important strategic decision in every organization. Mismatches in top management positions can severely impact a company. This thesis investigates the influence of the profile of newly appointed top executives in Swiss companies on the probability of turnover in the first years after their appointment, in a quantitative analysis of 77 Top Management Teams over a period of four years (2005-2008). Based on established research findings from the agency theory, the impact of the type of appointment (internal vs. external) is assessed on the likelihood of turnover. From the theory of "Homosocial Reproduction" and Schneider's attraction-selection-attrition model, the influence of dissimilarity on the probability of turnover is discussed.