The price of SPY, the largest ETF tracking the S&P 500: the 500 biggest US companies, weighted by size. Price only: dividends are left out.
Hover to inspect recorded values. Click to pin a point; click again to release. Drag between two points to measure the return over that span. Use arrow keys to move, shift with an arrow key to extend a span, Home or End to jump, and Escape to clear.