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Commodities and inflation

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Commodities and inflation

The relationship between commodity prices and inflation is the foundational argument for commodity ownership. The logic is intuitive: if you own the commodities that become more expensive when inflation rises, you preserve purchasing power. Historically, this has been true more often than not, but with important caveats.

The 1970s is the canonical commodity-inflation case study. US inflation accelerated from 4 percent in 1973 to 12 percent by 1975, then stayed elevated through the decade. Crude oil price surged from $3 per barrel in 1973 to $40 by 1979 (roughly 13-fold). Gold soared from $35 per ounce (fixed under Bretton Woods) to $850 (24-fold in nominal dollars, but much less in real inflation-adjusted terms). The S<P 500 delivered negative real returns (losses after inflation). Investors who owned commodity futures or precious metals were among the few winners.

However, the 1970s were anomalous. Inflation was driven by wage-price spirals and OPEC cartelization—not typical economic cycles. The 2000s saw inflation moderate, yet commodity supercycle driven by China's boom lasted through 2008. In the 2010s, inflation was subdued despite quantitative easing, and commodity prices collapsed. The 2021–2023 period saw inflation spike again, and commodities initially rallied, but the relationship was imperfect (oil outperformed grain).

The fundamental mechanism is: inflation erodes the purchasing power of cash and bonds. If you hold $1 million in cash earning 0 percent interest and inflation is 5 percent, you lose $50,000 in purchasing power annually. If you own $1 million of crude oil futures and crude rises 5 percent, you break even in real terms. Commodities, unlike bonds, have no yield but also no credit risk—they're pure assets.

Real assets (commodities, real estate, infrastructure) are theoretically superior to financial assets (stocks, bonds) during inflation. Real estate generates rent, which ideally rises with inflation; infrastructure generates regulated returns that adjust for inflation. Commodities generate neither, but they are the inputs to real assets, so they benefit directly. The relationship is: inflation increases input costs, which drives up real asset returns, which supports commodity prices.

Deflation is the opposite scenario. If prices fall 5 percent, holding cash is advantageous. Commodity prices fall in deflation, making commodity exposure a losing bet. The 2008–2009 financial crisis saw both commodity prices and stocks crash as deflation fears gripped markets. From a diversification standpoint, commodities are not a hedge against deflation (unlike Treasury bonds, which rally as rates fall and real yields become less negative).

Optimal commodity allocation depends on inflation expectations. If you expect 2–3 percent inflation (current Federal Reserve target), commodity allocation has been historically neutral to slightly negative (commodities underperform stocks due to lack of yield). If you expect 5–10 percent inflation (supply shocks, currency debasement, fiscal profligacy), commodity allocation is attractive (10–20 percent of portfolio). Commodity allocation is essentially a bet on inflation exceeding market consensus.

The correlation between commodity returns and inflation is inconsistent across time periods. From 1970–1980 (stagflation era), correlation was strongly positive. From 1980–2000 (disinflation era), correlation was negative—high real rates depressed commodities. From 2000–2008 (China boom), correlation was positive again. The takeaway: commodities correlate with inflation only when inflation is driven by supply shocks or demand surges, not when inflation is structural and real rates are high.

Modern portfolio theory suggests 5–15 percent allocation to commodities for long-term diversification. The rationale: commodities have low correlation to stocks and bonds, provide inflation hedging, and can rally during credit crises (oil spiked in March 2020 before falling, but gold stabilized portfolios). However, the allocation should be considered tactical, not permanent. In periods of expected deflation or very high real yields, commodity allocation should be reduced. In periods of supply shocks or rising inflation expectations, it should increase.

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