Global Asset Allocation Strategy

John is a portfolio manager at a wealth management firm, and he is considering the impact of global economic factors on his asset allocation strategies. He is particularly interested in how different regions are correlated and the potential benefits of diversifying across global markets.

He has the following assets in mind: U.S. equities, European equities, and emerging market equities. John's assessment indicates that the three markets can exhibit varying degrees of correlation depending on macroeconomic conditions.

To improve his portfolio's expected returns while managing risk, John needs to determine which approach to asset allocation would best capture global diversification opportunities while accounting for these correlations.

Which of the following asset allocation strategies would be the most appropriate for John to pursue in the context of global integration?