The CRSP U.S. Total Market Index is an index that reflects the overall performance of the U.S. stock market. It includes all stocks listed on the New York Stock Exchange, NASDAQ, and the American Stock Exchange. CRSP is the abbreviation of the Center for Research in Security Prices at the University of Chicago Business School, which has been collecting and analyzing data on the U.S. stock market since 1960.

The CRSP U.S. Total Market Index is calculated based on each stock's free-float market capitalization weighting, which means that each stock's weight in the index is proportional to the number of shares available for trading in the market. This approach avoids the influence of large companies or stocks controlled by a small number of holders, and better reflects the diversity and dynamics of the market.

The history of the CRSP U.S. Total Market Index can be traced back to December 31, 1925, when the benchmark point was 1,000 points. Since then, the index has weathered major market events such as the Great Depression, World War II, the tech bubble, the financial crisis and the COVID-19 pandemic.

The CRSP U.S. Total Market Index is a widely used benchmark index that many investors and fund managers use as a standard to measure their investment performance. At the same time, there are also some passive investment products, such as exchange-traded funds (ETFs) and index funds, which track the constituent stocks of the index, allowing investors to invest in the U.S. stock market at a low cost and with high efficiency.