An investor concerned with the downside risk of a black swan only needs a small portfolio to reap the benefits from diversification. This matches actual portfolio sizes, but does contrast with received wisdom from mean-variance analysis and intuition regarding fat tailed distributed returns. The concern for downside risk and the fat tail property of the distribution of returns can explain the low portfolio diversification. A simulation and calibration study is used to demonstrate the relevance of the theory and to disentangle the relative importance of the different effects.

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doi.org/10.1016/j.jedc.2012.03.007, hdl.handle.net/1765/76783
Journal of Economic Dynamics and Control
Erasmus School of Economics

Hyung, N., & de Vries, C. (2012). Simulating and calibrating diversification against black swans. Journal of Economic Dynamics and Control, 36(8), 1162–1175. doi:10.1016/j.jedc.2012.03.007