The Wilshire 5000 is a stock market index that aims to represent the performance of all publicly traded companies in the United States. It includes over 3,500 stocks, making it one of the broadest market indices available. The index is often used as a benchmark for the overall health of the U.S. stock market. Created in 1974, the Wilshire 5000 is weighted by market capitalization, meaning larger companies have a greater impact on the index's performance. Investors and analysts use it to gauge market trends and make informed investment decisions, reflecting the diverse landscape of American businesses.