Horses for Courses: Mean-Variance for Asset Allocation and 1/N for Stock Selection

Emmanouil Platanakis, Charles Sutcliffe, Xiaoxia Ye

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22 Citations (SciVal)
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For various organizational reasons, large investors typically split their portfolio decision into two stages - asset allocation and stock selection. We hypothesise that mean-variance models are superior to equal weighting for asset allocation, while the reverse applies for stock selection, as estimation errors are less of
a problem for mean-variance models when used for asset allocation than for stock selection. We confirm this hypothesis for US data using Bayes-Stein with no short sales and variance based constraints. Robustness checks with four other types of mean-variance model (Black-Litterman with three different reference portfolios, minimum variance, Bayes diffuse prior and Markowitz), and a wide range of parameter settings support our conclusions. We also replicate our core results using Japanese data, with additional replications using the Fama-French 5, 10, 12 and 17 industry portfolios and equities from seven countries. In contrast to previous results, but consistent with our empirical results, we show analytically that the superiority of mean-variance over 1/N is increased when the assets have a lower cross-sectional idiosyncratic volatility, which we also confirm in a simulation analysis calibrated to US data.
Original languageEnglish
Pages (from-to)302-317
Number of pages16
JournalEuropean Journal of Operational Research
Issue number1
Early online date6 Jun 2020
Publication statusPublished - 1 Jan 2021
Event7th Paris Financial Management Conference (2019) - Paris, France
Duration: 16 Dec 201918 Dec 2019


  • investment analysis
  • asset allocation
  • stock selection
  • mean-variance
  • naive diversification
  • portfolio theory

ASJC Scopus subject areas

  • Management Science and Operations Research
  • Economics, Econometrics and Finance (miscellaneous)


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