Commodity indices mask energy exposure

Broad commodity indices frequently fail as diversification tools because they concentrate risk in energy markets. Bruno Schwalbach notes that energy accounted for over half of the S&P GSCI weight in 2026 and carried roughly 85% of its historical risk (moontower). Even the BCOM index, which caps sectors at 33%, derives approximately half its risk from energy. This concentration creates a variance drag that reduces long-term compounded returns compared to the headline average annual return.

A balanced commodity strategy splits risk equally across six sectors, tilts toward trending markets, and moves to cash during broad downturns. This approach yielded 8.2% annually in backtests from 1996, compared to 2.8% for the GSCI, while maintaining a 0.29 correlation to global equities. Investors seeking broad exposure should separate strategic oil allocations from index-based commodity baskets, as mixing these motivations often leads to inefficient portfolio construction.