Global Financial Crises and Time‐Varying Volatility Comovement in World Equity Markets

This paper studies volatility comovement in world equity markets between 1994 and 2008. Global volatility factors are extracted from a panel of monthly volatility proxies relating to 25 developed and 20 emerging stock markets. A dynamic factor model (FM) is estimated using two‐year rolling‐window regressions. The FM's time‐varying variance shares of global factors map variations in volatility comovement over time and across countries. The results indicate that global volatility linkages are significantly stronger during financial crisis periods in Asia (1997‐1998), Brazil (1999), Russia (1998) and the United States (2000, 2007‐2008). Emerging markets are weakly synchronised with world volatility in comparison with developed markets. In particular, emerging market comovement is significantly lower than developed market comovement during the Asian and US sub‐prime crises. This suggests a degree of decoupling of emerging markets from the global drivers of volatility during these periods.     

Coopetition-based business models: The case of Amazon.com

Coopetition (collaboration between competing firms) is a phenomenon that has recently captured a great deal of attention due to its increasing relevance to business practice. However, current research on coopetition is still short on explaining how the potential advantages of coopetition can be realized over time as part of an individual firm's business model. In order to gain insights into this, we conduct a longitudinal, in-depth case study on the coopetition-based business models of Amazon.com. We find evidence of three distinct coopetition-based business models: (1) Amazon Marketplace, (2) Amazon Services and Web Services, and (3) the collaboration between Apple and Amazon on digital text platforms. We conclude by forwarding several propositions on how value can be created and captured by involving competitors in a firm's business model. As a whole, the results contribute to the current understanding of how firms – as well as their stakeholders – can better benefit from coopetition.     

Endogenous business cycle propagation and the persistence problem: The role of labor-market frictions

Contrasting sharply with a recent trend in DSGE modeling, we propose a business cycle model where frictions and shocks are chosen with parsimony. The model emphasizes a few labor-market frictions and shocks to monetary policy and technology. The model, estimated from U.S. quarterly postwar data, accounts well for important differences in the serial correlation of the growth rates of aggregate quantities, the size of aggregate fluctuations and key comovements, including the correlation between hours and labor productivity. Despite its simplicity, the model offers an answer to the persistence problem (Chari et al., 2000) that does not rely on multiple frictions and adjustment lags or ad hoc backward-looking components. We conclude modern DSGE models need not embed large batteries of frictions and shocks to account for the salient features of postwar business cycles.     

Correction to: Inside Buchanan’s Samaritan’s Dilemma: altruism,strategic courage and ethics of responsibility

Economics of Governance - The Samaritan’s Dilemma has largely been investigated, frequently by assuming that Samaritans help recipients out of altruism. Yet, Buchanan did not make any...     

Dynamic mean–variance problem with frictions

Finance and Stochastics - We study a dynamic mean–variance portfolio selection problem with return predictability and trading frictions from price impact. Applying mean-field type control...