What is the Wilshire 5000 index ?

The Wilshire 5000 Total Market Index, or more simply the Wilshire 5000, is a market-capitalization-weighted index of the market value of all stocks actively traded in the United States. Currently, the index contains over 4,100 components.[1] The index is intended to measure the performance of most publicly traded companies headquartered in the United States, with readily available price data, (Bulletin Board/penny stocks and stocks of extremely small companies are excluded). Hence, the index includes a majority of the common stocks and REITs traded primarily through New York Stock Exchange, NASDAQ, or the American Stock Exchange. Limited Partnerships and ADRs are not included. It can be tracked by following the ticker W5000.