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Statistical composite that measures changes in the economy or in financial markets, often expressed in percentage changes from a base year or from the previous month. Indexes measure the ups and downs of stock, bond, and some commodities markets, in terms of market prices and weighting of companies in the index.
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A statistical measure of the value of a certain portfolio of securities. The portfolio may be for a certain class of security, a certain industry, or may include the most important securities in a given market, among other options. The value of an index increases when the aggregate value of the underlying securities increases, and decreases when the aggregate value decreases. An index may track stocks, bonds, mutual funds, and any other security or investment vehicle, including other indices. An index's value may be weighted; for example, securities with higher prices or greater market capitalization may affect the index's value more than others. One of the most prominent examples of an index is the Dow Jones Industrial Average, which is weighted for price and tracks 30 stocks important in American markets.
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The relative value of a variable in comparison with itself on a different date. Many security price indicators such as the Standard & Poor's series and the New York Stock Exchange series are constructed as indexes. Also called stock index. See also base period.


To adjust a variable by a selected measure of relative value. For example, it has been proposed that an investor's basis on a security be indexed for changes in consumer prices so that only real increases in value will be taxed. Also called tax indexing. See also subindex.
Wall Street Words: An A to Z Guide to Investment Terms for Today's Investor by David L. Scott. Copyright © 2003 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved. All rights reserved.


An index reports changes up or down, usually expressed as points and as a percentage, in a specific financial market, in a number of related markets, or in an economy as a whole.

Each index -- and there are a large number of them -- measures the market or economy it tracks from a specific starting point. That point might be as recent as the previous day or many years in the past.

For those reasons, indexes are often used as performance benchmarks against which to measure the return of investments that resemble those tracked by the index.

A market index may be calculated arithmetically or geometrically. That's one reason two indexes tracking similar markets may report different results. Further, some indexes are weighted and others are not.

Weighting means giving more significance to some elements in the index than to others. For example, a market capitalization weighted index is more influenced by price changes in the stock of its largest companies than by price changes in the stock of its smaller companies.

Dictionary of Financial Terms. Copyright © 2008 Lightbulb Press, Inc. All Rights Reserved.


(1) A statistical indicator that measures changes in the economy in general or in particular areas.An example is the cost-of-living index.(2) A reference point against which measurements are taken for purposes of making future adjustments.An adjustable-rate mortgage might begin with an interest rate of 6 percent and provide that it will increase or decrease in a like percentage as the increase or decrease between today's quoted price for 10-year U.S.Treasury bonds and the price on the loan's annual anniversary date.We would say that 10-year T-bonds are the index.

Some leading loan indices include

• Wall Street Journal prime
• Federal discount rate
• Fed funds rate
• 11th District Cost of Funds
• 10-year Treasuries
• One-year LIBOR

The Complete Real Estate Encyclopedia by Denise L. Evans, JD & O. William Evans, JD. Copyright © 2007 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Biliary lipid concentration and cholesterol saturation index (CSI) in normolipemic and hypercholesterolemic rats.
Duane WC, Hunningnake DB, Freeman ML, Pooler PA, Schlojner L, Gebhurd RL (1988) Simvastatin, a competitive inhibitor of HMG CoA reductase lowers cholesterol saturation index of gallbladder bile.
Top graphs ((a) and (b)): mineral equilibrium diagram for XH01 (a) and SH02 (b) as representatives of studied geothermal water; middle graphs ((c) and (d)): FixAl results for reconstructing mineral equilibria in XH01 (c) and SH02 (d), fixing the Al concentration by equilibrium with albite and a 100% CO2 gas add back; bottom graphs ((e) and (f)): result showing equilibrium temperature estimations for the Xinzhou (e) and Shenzao (f) thermal waters using the combination of anhydrite/chalcedony saturation indexes (modified from Pastorelli et al.
WaterPOINT 870 is the first fully integrated field handheld system that provides an entire panel of key water quality tests, including measurements for pH, ORP, conductivity, free chlorine, total chlorine, monochloramine, ammonia, total dissolved solids, carbonate alkalinity, calcium hardness, Langelier saturation index, calcium, carbon dioxide, and temperature.
Assuming a pH of 7.5, a moderate calcium hardness of 300 ppm, 650 ppm alkalinity, 2000 ppm TDS, and a temperature of 85 degrees Fahrenheit result in a calculated Saturation Index (SI) of 1.0.
The saturation index (SI) was calculated theoretically from the conductivity; alkalinity, pH, and calcium values (Espigares Garcia & Perez Lopez, 1999).
It is important for techs to monitor pH levels because the number drastically impacts the Saturation Index equation--a formula used to diagnose water's chemical balance.
"If pH does change, for whatever reason, the Saturation Index changes," Lowry says.
That's because although both TA and pH figure into the Saturation index, pH has a larger impact on it.
On the other hand, the Saturation Index uses the actual pH reading in the formula--not a factor--so the change in the pH will have a profound effect on the outcome.
It is interesting that the trend slope declines sharply on the boundary of the saturation indexes -0.5 for witherite and -0.75 for fluorite.