Results from portfolio models for credit risk tell us that loan concentration in certain industry sectors can substantially increase the value-at-risk (VaR). The purpose of this paper is to analyze whether a tractable "infection model" can provide a meaningful estimate of the impact of...

This paper considers a theoretical model of n asymmetric firms that reduce their initial unit costs by spending on R&D activities. In accordance with Schumpeterian hypotheses we obtain that more efficient (bigger) firms spend more in R&D and this leads to a more concentrated market structure. We...

We model the impact of bank mergers on loan competition, reserve holdings and aggregate liquidity. A merger changes the distribution of liquidity shocks and creates an internal money market, leading to financial cost efficiencies and more precise estimates of liquidity needs. The merged banks...

Within the last three years, Google has acquired YouTube and DoubleClick and has attempted to control part of Yahoo!'s search advertising business. Two of the deals have not raised antitrust concerns by competition authorities. I review these deals with a focus on consumer welfare. Consumers are...

The retail sectors in many industrialized countries have experienced a large increase in concentration and the appearance of so-called \retail deserts\, areas of low retail provision. This study addresses the role of international trade in this process. The analysis shows that by raising product...

In this article, we simulate the concentration process within the German dairy sector employing a sector?wide optimization model. As a result, we get cost minimizing structures of the dairy sector for various time horizons depending on varying levels of transportation costs. We show that the...

This paper studies competition in prices and opening hours in a model with free entry. It is shown that under free competition a market failure arises: Entry is excessive and opening hours are under-provided. Restrictions on opening hours aggravate this failure. I analyze the impact of a...

This paper solves one of the puzzles in the analysis of regional and industrial distributions of economic activity, the discrepancy between absolute and relative measures. It shows that the difference between an absolute and a relative Theil index of localization can be expressed in terms of...

Since objective news coverage is vital to democracy, captured media can seriously distort collective decisions. The current paper develops a voting model where citizens are uncertain about the welfare effects induced by alternative policy options and derive information about those effects from...