In press and analyst reports, the prevailing opinion is expressed that diversified companies destroy shareholder value and are therefore traded at a discount on the stock market. Until now, there has been no scientific evidence for this thesis in Germany, nor has there been an analysis of the influencing factors on discount or premium. Through an extensive empirical study, Philip Beckmann demonstrates that a significant diversification discount exists, albeit with high variance. There are also diversified companies that are traded at a premium. The specific influencing factors of such valuation differences are systematically identified and examined for their effect on a discount or premium.