Mosaic Finance
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Brinson-style decomposition of S&P 500 returns into GICS sector contributions
Sector Contribution = sector weight x rolling compounded sector ETF return over the selected lookback window. The sum of all 11 sector contributions approximates the SPY index return.
Returns mode divides out the sector weight to show raw sector ETF performance, making it easier to compare sectors of different sizes.
Data source:Yahoo Finance daily closes for SPY and 11 S&P 500 GICS sector ETFs (XLK, XLF, XLV, XLY, XLI, XLC, XLP, XLE, XLRE, XLU, XLB). Weights are approximate market-cap weights and are held constant.
When the S&P 500 goes up 1%, not every sector contributes equally. This page breaks down the index return into its 11 sector components (tech, financials, healthcare, energy, etc.) so you can see which sectors are actually driving the market. For example, a rally led by defensive sectors like utilities and healthcare tells a very different story than one led by tech and consumer discretionary. It helps answer: "Where are the returns really coming from?"