A mutual fund or ETF that seeks to replicate the broad market by holding the stock of every security that trades on a certain exchange, invests in a certain country, or passes basic thresholds of size (market cap) or trading volume. Total stock funds, also called total stock market index funds or total market funds, may track a broad index such as the Wilshire 5000, Russell 2000 or MSCI U.S. Broad Market. Taobiz explains Total Stock Fund These super-broad index funds tend to have less volatility than even large indexes like the S&P 500 just because they hold so many companies’ stock. Most total stock funds will have portfolio weightings based in some way on market cap, but they are not necessarily just market-cap weighted, like the S&P 500 is. Total stock funds may not capture a full 100% of the market capitalization of their target market (such as the whole United States or all small-cap stocks), but they are usually able to capture 95% or more by owning the first few thousand stocks in order of market capitalization. One of the largest and oldest total stock funds is the Vanguard Total Stock Market Index Fund, which has nearly $100 billion in assets and owns the 1,300 largest companies that trade on the NYSE, AMEX and Nasdaq.