https://hdl.handle.net/10419/120 2026-09-16T22:17:47Z https://hdl.handle.net/10419/76793 Title: What is the impact of stock market contagion on an investor's portfolio choice? Authors: Branger, Nicole; Kraft, Holger; Meinerding, Christoph Abstract: Stocks are exposed to the risk of sudden downward jumps. Additionally, a crash in one stock (or index) can increase the risk of crashes in other stocks (or indices). Our paper explicitly takes this contagion risk into account and studies its impact on the portfolio decision of a CRRA investor both in complete and in incomplete market settings. We find that the investor significantly adjusts his portfolio when contagion is more likely to occur. Capturing the time dimension of contagion, i.e. the time span between jumps in two stocks or stock indices, is thus of first-order importance when analyzing portfolio decisions. Investors ignoring contagion completely or accounting for contagion while ignoring its time dimension suffer large and economically significant utility losses. These losses are larger in complete than in incomplete markets, and the investor might be better off if he does not trade derivatives. Furthermore, we emphasize that the risk of contagion has a crucial impact on investors' security demands, since it reduces their ability to diversify their portfolios. 2009-01-01T00:00:00Z https://hdl.handle.net/10419/39044 Title: Investment, income, and incompleteness Authors: Bick, Björn; Kraft, Holger; Munk, Claus Abstract: The utility-maximizing consumption and investment strategy of an individual investor receiving an unspanned labor income stream seems impossible to find in closed form and very difficult to find using numerical solution techniques. We suggest an easy procedure for finding a specific, simple, and admissible consumption and investment strategy, which is near-optimal in the sense that the wealthequivalent loss compared to the unknown optimal strategy is very small. We first explain and implement the strategy in a simple setting with constant interest rates, a single risky asset, and an exogenously given income stream, but we also show that the success of the strategy is robust to changes in parameter values, to the introduction of stochastic interest rates, and to endogenous labor supply decisions. 2009-01-01T00:00:00Z https://hdl.handle.net/10419/39051 Title: Does IT standardization help to boost cost and profit efficiency? Empirical evidence from German savings banks Authors: Noth, Felix; Slotty, Constantin; Hackethal, Andreas Abstract: This paper investigates the impact of IT standardization on bank performance based on a panel of 457 German savings banks over the period from 1996 to 2006. We measure IT standardization as the fraction of IT expenses for centralized services over banks' total IT expenses. Bank efficiency, in turn, is measured by traditional accounting performance indicators as well as by cost and profit efficiencies that are estimated by a stochastic frontier approach. Our results suggest that IT standardization is conducive to cost efficiency. The relation is positive and robust for small and medium-sized banks but vanishes for very large banks. Furthermore, our study confirms the often cited computer paradox by showing that total IT expenditures negatively impact cost efficiency and have no influence on bank profits. To the best of our knowledge, this paper is first to empirically explore whether IT standardization enhances efficiency by employing genuine data of banks' IT expenditures. 2009-01-01T00:00:00Z https://hdl.handle.net/10419/39049 Title: Financial constraints and the decision to lease: Evidence from German SME Authors: Slotty, Constantin Abstract: The objective of this paper is to test the hypothesis that in particular financially constrained firms lease a higher share of their assets to mitigate problems of asymmetric information. The assumptions are tested under a GMM framework which simultaneously controls for endogeneity problems and firms' fixed effects. We find that the share of total annual lease expenses attributable to either finance or operating leases is considerably higher for financially strained as well as for small and fast-growing firms those likely to face higher agency-cost premiums on marginal financing. Furthermore, our results confirm the substitution of leasing and debt financing for lessee firms. However, we find no evidence that firms use leasing as an instrument to reduce their tax burdens. 2009-01-01T00:00:00Z