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...

Since the early 1990s an unprecedented process of consolidation has taken place in the banking sector in most industrialised countries raising concern of policymakers that it may reduce access to credit for the small business sector. While most of the existing empirical studies have focused on...

Eine Welle von Fusionen hat die Weltwirtschaft erfasst. Allein die Dimension der bei Großfusionen genannten Summen, die nicht selten das Bruttoinlandsprodukt von Volkswirtschaften übersteigen, führen zu einem erheblichen Maß an Verunsicherung. Dies wird auch in den Überschriften von...

Substantial increases in retail concentration (particularly in Europe) raise concerns about the welfare implications for consumers. In a formal model, we argue that retailer market power reduces upstream firms incentives to introduce new products. On the basis of a survey of firms in German food...

The last couple of decades have seen an increased retail concentration around the world, particularly in Europe. Views on the welfare implications of this severe change are controversial. Consumers might benefit because larger stores (owned by larger retailer chains) offer more product choices....

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...

We found hierarchical structure and negative degree correlation in firms' transaction network. The network consists of 800,000 Japanese firms. We also summarize other features of the network and discuss why studying network structure is important. We also found scale free distribution in...

Theory predicts a positive relationship between market concentration and profitability in most scenarios. In empirical work, however, this relation is frequently not found or only a weak connection is observed. We compare the performance of concentration and market share variables, which are...

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...