The term S&P Total Market Index refers to a composite that includes large, mid, small, and micro-cap stocks. The S&P Total Market Index is published and maintained by S&P Dow Jones Indices.
Also referred to as the S&P TMI, the S&P Total Market Index was designed to track the entire equity market of the United States. This includes large, mid, small and micro-cap stocks. All of the other U.S. equities indices tracked by S&P are a subset of the TMI.
While the S&P 500 accounts for nearly 80% of the total market capitalization of U.S. common equities, the S&P Total Market Index provides an even broader, and more diverse, measure of the market's performance. Launched on March 27, 2006, the index contains over 3,800 securities. The performance of the index can be tracked using the stock ticker SPTMI.