Stock market index

A stock index or stock market index is a measurement of a section of the stock market. It is computed from the prices of selected stocks (typically a weighted average). It is a tool used by investors and financial managers to describe the market, and to compare the return on specific investments. A stock index or stock market index is a measurement of a section of the stock market. It is computed from the prices of selected stocks (typically a weighted average). It is a tool used by investors and financial managers to describe the market, and to compare the return on specific investments. Two of the primary criteria of an index are that it is investable and transparent: the method of its construction should be clear. Many mutual funds and exchange-traded funds attempt to 'track' an index (see index fund) with varying degrees of success. The difference between an index fund's performance and the index is called tracking error. Stock market indices may be classified in many ways. A 'world' or 'global' stock market index — such as the MSCI World or the S&P Global 100 — includes stocks from multiple regions. Regions may be defined geographically (e.g., Europe, Asia) or by levels of industrialization or income (e.g., Developed Markets, Frontier Markets). A 'national' index represents the performance of the stock market of a given nation—and by proxy, reflects investor sentiment on the state of its economy. The most regularly quoted market indices are national indices composed of the stocks of large companies listed on a nation's largest stock exchanges, such as the American S&P 500, the Japanese Nikkei 225, the Indian NIFTY 50, and the British FTSE 100. Many indices are regional, such as the FTSE Developed Europe Index or the FTSE Developed Asia Pacific Index. Indexes may be based on exchange, such as the NASDAQ-100 or NYSE US 100, or groups of exchanges, such as the Euronext 100 or OMX Nordic 40. The concept may be extended well beyond an exchange. The Wilshire 5000 Index, the original total market index, represents the stocks of nearly every publicly traded company in the United States, including all U.S. stocks traded on the New York Stock Exchange (but not ADRs or limited partnerships), NASDAQ and American Stock Exchange. Russell Investment Group added to the family of indices by launching the Russell Global Index. More specialized indices exist tracking the performance of specific sectors of the market. Some examples include the Wilshire US REIT which tracks more than 80 American real estate investment trusts and the Morgan Stanley Biotech Index which consists of 36 American firms in the biotechnology industry. Other indices may track companies of a certain size, a certain type of management, or even more specialized criteria — one index published by Linux Weekly News tracks stocks of companies that sell products and services based on the Linux operating environment. Some indices, such as the S&P 500, have multiple versions. These versions can differ based on how the index components are weighted and on how dividends are accounted for. For example, there are three versions of the S&P 500 index: price return, which only considers the price of the components, total return, which accounts for dividend reinvestment, and net total return, which accounts for dividend reinvestment after the deduction of a withholding tax. As another example, the Wilshire 4500 and Wilshire 5000 indices have five versions each: full capitalization total return, full capitalization price, float-adjusted total return, float-adjusted price, and equal weight. The difference between the full capitalization, float-adjusted, and equal weight versions is in how index components are weighted. An index may also be classified according to the method used to determine its price. In a price-weighted index such as the Dow Jones Industrial Average, NYSE Arca Major Market Index, and the NYSE Arca Tech 100 Index, the price of each component stock is the only consideration when determining the value of the index. Thus, price movement of even a single security will heavily influence the value of the index even though the dollar shift is less significant in a relatively highly valued issue, and moreover ignoring the relative size of the company as a whole. In contrast, a capitalization-weighted (also called market-value-weighted) index such as the S&P 500 or Hang Seng Index factors in the size of the company. Thus, a relatively small shift in the price of a large company will heavily influence the value of the index.