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What is an 'Index'

An index is an indicator or measure of something, and in finance, it typically refers to a statistical measure of change in a securities market. In the case of financial markets, stock and bond market indices consist of an imaginary portfolio of securities representing a particular market or a portion of it. In reference to mortgages, it refers to a benchmark interest rate created by a third party.

BREAKING DOWN 'Index'

Each index related to the stock and bond markets has its own calculation methodology. In most cases, the relative change of an index is more important than the actual numeric value representing the index. For example, if the Financial Times Stock Exchange (FTSE) 100 is at 6,670.40, that number tells investors the index is nearly seven times its base level of 1,000. However, to assess how the index has changed from the previous day, investors must look at the amount the index has fallen, often expressed as a percentage.

Relationship Between Trading Indices, Mutual Funds and Exchange-Traded Funds

When putting together mutual funds and exchange-traded funds (ETFs), fund sponsors attempt to create portfolios mirroring the components of a certain index. This allows an investor to buy a security likely to rise and fall in tandem with the stock market as a whole or with a segment of the market.

Examples of Trading Indices

The Standard & Poor's 500 is one of the world's best known indices and one of the most commonly used benchmarks for the stock market. It includes 70% of the total stocks traded in the United States. Conversely, the Dow Jones Industrial Average (DJIA) is also a very well-known index, but it only represents stock values from 30 of the nation's publicly traded companies. Other prominent indices include the DJ Wilshire 5000; the MSCI EAFE, which includes foreign stocks based in Europe, Australasia and the Far East; and the Lehman Brothers Aggregate Bond Index.

Definition of Indexed Annuity

Like mutual funds, indexed annuities are tied to a trading index. However, rather than the fund sponsor trying to put together an investment portfolio likely to closely mimic the index in question, these securities feature a rate of return that follows a particular index but typically have caps on the returns they provide. For example, if an investor buys an annuity indexed to the Dow Jones and it has a cap of 10%, its rate of return will be between 0 and 10%, depending on the annual changes to that index. Indexed annuities allow investors to buy securities that grow along with broad market segments or the total market.

Mortgage Index

Adjustable-rate mortgages (ARMs) feature interest rates that adjust over the life of the loan. The adjustable interest rate is determined by adding a margin to an index. One of the most popular mortgage indices is the London Interbank Offer Rate (LIBOR). For example, if a mortgage indexed to the LIBOR has a 2% margin and the LIBOR is 3%, the interest rate on the loan is 5%.

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    To answer this question, we should first define exactly what an index fund is. An index fund is a mutual fund, or a basket ... Read Answer >>
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