Empirically Robust Pareto Dominance of NASDAQ-Gold Portfolios in 2009–2024 JPY-Denominated Data

This working paper documents an empirically robust phenomenon observed in 2009–2024 JPY-denominated return data. Using exhaustive enumeration of 1,001 portfolio allocations across five major asset classes (NASDAQ 100, S&P 500, Gold, ACWI, and Nikkei 225), the study constructs the Pareto frontier based on Sharpe ratio and CAGR. The results show that portfolios combining NASDAQ 100 and Gold consistently occupy Pareto-optimal positions, while ACWI and Nikkei 225 are absent from the frontier. Additional analyses include sub-period robustness tests, USD-denominated replication, and validation of CAGR approximation. The paper proposes two candidate explanations: structural low correlation between risk-on and risk-off assets, and a yen-denominated amplification effect. Theoretical derivation remains an open problem.