Sector rotation patterns reveal where we are in the business cycle. The classic rotation model: (1) Early Recovery — cyclicals lead (Consumer Discretionary, Industrials, Financials, Real Estate). Fed starts cutting rates. (2) Mid Cycle/Expansion — Technology and Communication Services lead as earnings grow. The longest phase. (3) Late Cycle — Energy and Materials outperform as commodity prices rise with inflation. Defensive sectors start rotating in. (4) Recession — Utilities, Healthcare, and Consumer Staples outperform. Yields fall, gold rises. How to track: compare relative performance of sector ETFs (XLK, XLF, XLE, XLU, etc.) over rolling 1-3 month periods. When defensive sectors start outperforming cyclicals while yields are still high, it's a classic late-cycle warning. Cross-reference with PMI, yield curve, and credit spreads for confirmation.