The heatmap displays quarterly returns across U.S. industry sectors from 2008 to 2025. Each row represents a sector, each column a year, and each dot corresponds to that sector’s quarterly performance—blue for gains, red for losses. Most periods are dominated by blue dots, confirming that equity markets tend to rise over time in aggregate. However, the visualization also shows that during extreme episodes, sectors move more tightly together. Waves of uniform blue in boom phases and uniform red during events such as the 2008 financial crisis reveal heightened comovement across industries. 

Data: Monthly value-weighted returns with dividends for 49 industry portfolios, 2008–2025, from the Kenneth R. French Data Library (Fama–French Research Data Factors). Returns are compounded quarterly and exclude transaction costs, management fees, and taxes.