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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 ?
Out of 48 patients, 27(54%) patients with post-infective pulmonary fibrosis had apnea-hypopnea index less than five, 10(20%) patients had apnea-hypopnea index 5-14, 8(16%) had apnea-hypopnea index 15-29 and 3(6%) had AHI equal or more than 30.
[+ or -]SD./n-% Age 48 23 82 48.5 [+ or -]11.7 Female 62 19.3% Male 259 80.7% Weight (kg) 86 52 143 89 [+ or -]15.5 Height (cm) 172 80 200 171.7 [+ or -]9.9 BMI 29.4 16 57.6 30.1 [+ or -]5.1 AHI: apnea-hypopnea index; ESS: Epworth sleepiness scale; OSA: obstructive sleep apnea; BMI: body mass index; SD: standard deviation Table 2.
In an unadjusted analysis, patients with an apnea-hypopnea index of more than 20 were 4.13 times more likely to have a stroke, compared with patients who did not have OSA.
All 66 children with ADHD had apnea-hypopnea index scores between 1 and 5 (mild apnea) before treatment.
In 10 women referred for sleep-disordered breathing in the third trimester, the investigators found that significant improvements in the apnea-hypopnea index and minimum arterial oxyhemoglobin saturation occurred in all 10 postnatally.
Polysomnography was performed on all subjects in a sleep laboratory, and the average number of episodes of apneas and hypopneas per hour of sleep (apnea-hypopnea index) was calculated.
Significant associations with crash risk were seen for a higher apnea-hypopnea index, fewer hours of sleep, and self-reported excessive sleepiness.
However, obstructive sleep apnea (apnea-hypopnea index of more than two episodes/hour) was common in both groups (8.2% of the caffeine group and 11% of the placebo group; P = .22).
Sleep apnea severity was assessed with the apnea-hypopnea index (AHI), which indicates severity based on the number of apneas (complete cessation of airflow) and hypopneas (partial cessation of airflow) per hour of sleep.
(4) The apnea-hypopnea index (AHI), also known as the respiratory disturbance index, is the sum of the number of apneic and hypopneic events per hour during sleep, and it indicates the severity of OSA.
In the first study, conducted among 68 people with a high likelihood of sleep apnea, the apnea-hypopnea index on CPAP and Sleep Apnea Quality of Life Index scores at 3 months did not differ significantly between a sleep lab approach and an ambulatory approach (Ann.
The mean apnea-hypopnea index prior to surgery was 25 among the children with OSAS and 3 among those with SDB.