Final answer:
The Standard & Poor's 500 index (S&P 500) is often considered the broadest measure of the overall stock market, with the Wilshire 5000 also being a comprehensive index compared to the narrower Dow Jones Industrial Average (DJIA).
Step-by-step explanation:
The broadest measure of the activity and movement of the overall stock market is often considered to be the Standard & Poor's 500 index (S&P 500). This index is a weighted average of the market capitalization of the 500 largest firms listed on stock exchanges in the United States. Another commonly referenced measure is the Dow Jones Industrial Average (DJIA), although it is based on only 30 large U.S. companies' stock prices, making it less broad than the S&P 500. Additionally, the Wilshire 5000 is a more comprehensive index that tracks the stock prices of essentially all publicly traded U.S. companies, making it another broad measure of market performance.