We set up a general equilibrium model, in which offshoring to a low-wage country can lead to job polarisation in the high-wage country. Job polarisation is the result of a reallocation of labour across firms that differ in productivity and pay wages that are positively linked to their profits by a rent-sharing mechanism. Offshoring involves fixed and task-specific variable costs, and as a consequence it is chosen only by the most productive firms, and only for those tasks with the lowest variable offshoring costs. A reduction in those variable costs increases offshoring at the intensive and at the extensive margin, with domestic employment shifted from the newly offshoring firms in the middle of the productivity distribution to firms at the tails of this distribution, paying either very low or very high wages. We also study how the reallocation of labour across firms affects economy-wide unemployment. Offshoring reduces unemployment when it is confined to high-productivity firms, while this outcome is not guaranteed when offshoring is also chosen by low-productivity firms.

Zusammenfassung Die Dissertation behandelt die Thematik der Unternehmensheterogenität. Die Arbeit besteht aus einem theoretischen und einem empirischen Teil. Im theoretischen Teil wird untersucht, wie sich Asymmetrien auf der Ebene der Konsumenten auf das Unternehmensverhalten auswirken. Im empirischen Teil wird die Frage behandelt, in welchem Maße die Performance von Firmen innerhalb der gleichen Industrie differiert. Kapitel 1 führt in die Literatur zur Unternehmensheterogenität ein. Kapitel 2 gibt einen Überblick über die aktuelle Literatur zu den Modellen der Horizontalen Produktdifferenzierung. In Kapitel 3 wird das Hotelling-Duopolmodell nach d'Aspremont, Gabszewicz und Thisse (1979) in Bezug auf die Anzahl der Spieler generalisiert. Es kann gezeigt werden, dass die Anzahl der Spieler einen Einfluss auf das Niveau der Differenzierung besitzt. Das Prinzip der Maximalen Differenzierung im Duopol verliert seine Gültigkeit für den Oligopolfall. In Kapitel 4 wird das Investitionsverhalten in neue Distributionstechnologien in Märkten mit Wechselkosten der Konsumenten mit Hilfe eines Realoptionsmodells analysiert. Kapitel 5 umfasst den empirischen Teil der Arbeit. Hier wird statistisch untersucht, ob innerhalb der Industrien Firmen langfristig eine ähnliche Performance aufweisen (Performancegruppen) und welchen Anteil der Varianz der Firmen durch diese gruppierten Unternehmen erklärt wird. Schlagwörter: Firmenheterogenität, Horizontale Produktdifferenzierung, Realoptionen, Wechselkosten, Strategische Gruppen / Abstract The dissertation considers the heterogenity of firms. It consists of a theoretical and an empirical part. In the theoretical part it is examined to what extent asymmetries between customers have an impact on firm behavior. In the empirical part, the author analyzes the level of heterogeneity of firm performance within industries. Chapter 1 introduces the reader into the topic of firm heterogeneity. Chapter 2 provides an overview over the recent literature on horizontal product differentiation. In Chapter 3 the Hotelling duopoly model à la d'Aspremont, Gabszewicz and Thisse (1979) is generalized with respect to the number of firms. It is shown that the number of firms has an impact on the level of product differentiation. The Principle of Maximum Differentiation valid for the duopoly does not hold for the oligoply case. In Chapter 4, the optimal investment in a new distribution technology in markets with consumer switching costs is investigated using a real option model. Chapter 5 corresponds to the empirical part of the dissertation. It is studied if there are firms within industries with a similar long-run performance (performance groups) and how much of the total variance of the firm profits are explained by these firm groups. Key words: firm heterogeneity, horizontal product differentiation, real options, switching costs, strategic groups

We set up a general equilibrium model, in which offshoring to a low-wage country can lead to job polarisation in the high-wage country. Job polarisation is the result of a reallocation of labour across firms that differ in productivity and pay wages that are positively linked to their profits by a rent-sharing mechanism. Offshoring involves fixed and task-specific variable costs, and as a consequence it is chosen only by the most productive firms, and only for those tasks with the lowest variable offshoring costs. A reduction in those variable costs increases offshoring at the intensive and at the extensive margin, with domestic employment shifted from the newly offshoring firms in the middle of the productivity distribution to firms at the tails of this distribution, paying either very low or very high wages. We also study how the reallocation of labour across firms affects economy-wide unemployment. Offshoring reduces unemployment when it is confined to high-productivity firms, while this outcome is not guaranteed when offshoring is also chosen by low-productivity firms.