Stock index is a relative index reflecting the changes of stock prices at different time points. Usually, the stock price in the reporting period is compared with the fixed base period price, and the ratio of the two is multiplied by the index value of the base period, which is the stock index in the reporting period. There are three methods to calculate stock index: one is relative method, the other is comprehensive method, and the third is weighting method.
(1) relative method
The relative method, also known as the average method, is to calculate the stock index of each sample first. Add up and get the arithmetic average of the total. Its calculation formula is:
Stock index = the sum of n sample stock indexes /n The Economist common stock index in Britain adopts this calculation method.
(2) Comprehensive method
The comprehensive method is to add the base period and reporting period prices of sample stocks respectively, and then compare them to get the stock index. Namely:
Stock index = sum of stock prices in the reporting period/sum of stock prices in the base period.
Substitution number:
Stock price index = (8+12+18)/(5+8+10+15) = 52/38 =136.8.
That is, the share price in the reporting period rose by 36.8% compared with the base period.
Judging from the calculation of stock index by average method and comprehensive method, the factors such as the different circulation and trading volume of various sample stocks and the different influence on the stock price of the whole stock market are not taken into account, so the calculated index is not accurate enough. In order to accurately calculate the stock index, it is necessary to add weight, which can be either volume or circulation.
(3) Weighting method
The weighted stock index is weighted according to the relative importance of sample stocks in each period, and its weight can be the number of shares traded and the stock circulation. According to the time division, the weight can be the number of basic options or the number of reported options. The index weighted by the number of shares traded in the base period (or circulation disk) is called Rasbel index; An index weighted by the number of stocks traded (or circulated) during the reporting period is called the quotation index.
Rasbell index focuses on the number of shares traded in the base period (or circulation), while Paixu index focuses on the number of shares traded in the reporting period (or circulation). At present, most stock indexes in the world are Pais indexes.
Several famous stock indexes in the world
Dow Jones stock index
The Dow Jones stock index is the oldest stock index in the world, and its full name is the average stock price. Prepared by charles dow, founder of Dow Jones Company, on 1884. Its original Dow Jones stock price average index is based on 1 1 representative railway companies, calculated and compiled by arithmetic average method, and published in the Daily Communication edited and published by charles dow himself. Its calculation formula is:
Average share price = sum of selected stock prices/number of selected stocks. Starting from 1897, the Dow Jones average stock price index is divided into two categories: industry and transportation, in which the industrial average stock price index includes 12 stocks and the transportation average index includes 20 stocks, which are published in the Wall Street Journal published by Dow Jones Company. 1929, the Dow Jones stock price average index added utility stocks, making it include 65 stocks, which have continued to this day.
At present, the average Dow Jones stock price index is based on 1928 65438+ 10/month. Because the average price of Dow Jones stock at the close of this day is about 100, it is set as the benchmark date. In the future, the percentage calculated by comparing the stock price with the benchmark date becomes the voting price index of each period, so the current stock index is generally based on points, and the rise and fall of each point of the stock index is the percentage of the rise and fall relative to the benchmark date.
The initial calculation method of Dow Jones stock price average index is simple arithmetic average method. When the stock is ex-dividend, the stock index will be discontinuous. After 1928, the Dow Jones stock average price index was changed to a new calculation method, that is, the connection technology was adopted when the stock was ex-dividend or ex-dividend, so as to ensure the continuity of the stock index, make the stock index more perfect and gradually spread to the whole world.
At present, the Dow Jones stock price average index is divided into four groups. The first group is the average index of industrial stock prices. It is composed of 30 representative stocks of large industrial and commercial companies, which become larger with the development of economy, and can roughly reflect the price level of the entire industrial and commercial stocks in the United States, which is also the average price of Dow Jones Industrial Stock that people usually quote. The second group is the average stock price index of the transportation industry.
Including the shares of 20 representative transportation companies, namely, 8 railway transportation companies, 8 airlines and 4 road freight companies. The third group is the average share price index of public utilities, which consists of 1 5 stocks of gas companies and power companies representing American public utilities. The fourth group is the average price composite index.
It is a comprehensive index composed of 65 stocks in the first three groups of stock price average indexes. Although this group of comprehensive indexes provides direct stock market conditions for dominant stocks, the first group-industry stock price average index is usually cited now.
Dow Jones average stock price index is the most influential and authoritative stock price index in the world at present. One of the reasons is that the stocks selected by the Dow Jones average share price index are representative, and the issuing companies of these stocks are all famous companies with important influence in the industry. Their share prices have attracted the attention of the world stock market, and investors from all countries attach great importance to them. In order to maintain this feature, Dow Jones often adjusts the stocks selected by its stock price average index, and replaces those stocks that lose their representativeness with dynamic and more representative company stocks. Since 1928, 30 kinds of industrial and commercial company stocks used only to calculate the average price index of Dow Jones Industrial Average have been replaced 30 times. Almost every two years, the stock of a new company will replace the stock of the old company. The second reason is that The Wall Street Journal, the news media that publishes the Dow Jones stock price average index, is the most influential newspaper in the financial sector. The newspaper reported in detail the average index, percentage change rate of each sample stock and the turnover of each sample stock calculated every hour every day, and paid attention to the stock price average index after share split's correction. During the business hours of the new york Stock Exchange, the Dow Jones average stock price index is published every half hour. The third reason is that this average stock price index has never stopped since its compilation, and it can be used to compare the stock market and economic development in different periods. It has become one of the most sensitive average stock price indexes reflecting the changes in the American stock market, and it is the main reference for observing market dynamics and engaging in stock investment. Of course, because dow jones stock price indexes is a constituent stock index, its representativeness has been questioned and criticized by people, because it only includes a very small part of more than 2,500 listed companies, and most of them are active stocks, excluding companies in the service industry and financial industry that have developed rapidly in recent years.
Standard & Poor's stock price index
In addition to dow jones stock price indexes, the Standard & Poor's share price index is also very influential in the United States. It is the stock price index compiled by Standard & Poor's Company, the largest securities research institution in the United States. The company began to compile and publish the stock price index on 1923. Initially, 230 stocks were selected and two stock price indices were compiled. By 1957, the range of this stock price index has expanded to 500 stocks, divided into 95 combinations. The four most important groups are industrial group, railway group, public utility group and 500-share mixed group. From 1 July 9761,it was changed to 400 industrial stocks, 20 transportation stocks, 40 public utilities stocks and 40 financial stocks. For decades, although the stock has changed, it has always remained at 500. Standard & Poor's stock price index is based on the average market price of sample stocks from 194 1 to 1943, weighted by the number of listed stocks, and weighted by the base period, and its base is 10. Take the current stock market price multiplied by the number of shares issued in the stock market as the numerator, the base stock market price multiplied by the number of shares in the base period as the denominator, and the divided number multiplied by 10 as the stock price index.
New york Stock Exchange Stock Price Index
Stock price index of new york Stock Exchange. This is the stock price index compiled by new york Stock Exchange. Since June, 1966. First, the common stock price index was changed to a mixed index, including 1570 stocks of 1500 companies listed on new york Stock Exchange. The specific calculation method is to arrange these stocks according to the price level, and calculate the price indexes of industrial stocks, financial stocks, public utilities stocks and transportation stocks respectively. The largest and most extensive is the industrial stock price index, which consists of 1093 stocks; The financial stock index includes 223 stocks including investment companies, savings and loan associations, installment financing companies, commercial banks, insurance companies and real estate companies. The stock price index of transportation industry includes 65 stocks of railway, aviation, ship and automobile companies; The stock price index of public utilities includes shares of telephone and telegraph company, gas company, electric power company and post and telecommunications company 189.
New york's stock price index is based on196565438+50 points determined on February 3 1 day, and adopts the form of comprehensive index. The new york Stock Exchange announces the changes of the index every half hour. Although new york Stock Exchange has not compiled a stock price index for a long time, it is welcomed by investors because it can comprehensively and timely reflect the comprehensive situation of its stock market activities.
Nikkei Jones stock index (Nikkei average share price)
It is the average stock price compiled and published by Japan Economic News Agency, which reflects the price changes of Japanese stock market. The index was compiled from September 1950.
Initially, the revised average share price was calculated based on the shares of 225 companies listed on the first market of Tokyo Stock Exchange, which was then called "Zhengdong revised average share price". On may 1975 and may 1 day, the nihon keizai shimbun bought a trademark from Dow Jones, which was calculated by the correction method of American Dow Jones, and the stock index was renamed as "Nikkei Jones average share price". 1 985 may1day, when the contract expires 10 year, the name was changed to "Nikkei average share price" through negotiation between the two companies.
According to the sample number of the calculation object, the index is divided into two types, one is the average price of 225 Nikkei stocks. The selected samples are all stocks listed in the primary market of Tokyo Stock Exchange, and will not change in principle after the samples are selected. 198 1 year, manufacturing enterprises 150, construction enterprises 10, aquaculture enterprises 3, mining enterprises 3, commerce enterprises 12, road transport and maritime transport enterprises 14, finance and finance. Because the average share price of 225 Nikkei stock indexes has been continuous from 1950, its continuity and comparability are good, and it has become the most commonly used and reliable index to investigate and analyze the long-term evolution and dynamics of Japanese stock market. Another index is the average share price of the Nikkei 500 index. This is compiled by 1982 1.4. Because its sample includes 500 kinds of stocks, its representation is relatively broader, but its sample is not fixed. In April each year, samples are changed according to the operating conditions, transaction volume, transaction amount and total market value of listed companies.
Financial Times Stock Price Index
The full name of the Financial Times stock price index is "London Financial Times Industrial and Commercial Common Stock Price Index", which is published by the Financial Times. The stock price index includes 30 representative publicly listed common stocks selected from British industry and commerce. It takes 1 935 July1as the base period, and its base point is 100. The stock price index is famous for showing the London stock market in time.
Hong kong hang seng index
Hong Kong Hang Seng Index is the oldest and most influential stock price index in Hong Kong stock market. Promulgated by Hang Seng Bank of Hong Kong on June 24th, 1969 165438.
The Hang Seng Stock Index consists of 33 representative and economically powerful stocks selected from more than 500 listed companies in Hong Kong, which are divided into four categories-4 financial stocks, 6 public utility stocks, 9 real estate stocks and 65,438+04 other industrial and commercial stocks (including aviation and hotels).
These stocks account for 63.8% of the market value of Hong Kong stocks, because the stock index involves various industries in Hong Kong and is very representative.
The compilation of Hang Seng Stock Index is based on July 3 1, 1, 964, because the Hong Kong stock market operated normally on this day, and the turnover value was even, which can reflect the basic situation of the whole Hong Kong stock market. The base point is determined as 100 point. The calculation method is to multiply the daily closing price of 33 kinds of stocks by their respective issued shares as the market value of the calculation day, then compare it with the market value of the base period, and then multiply it by 100 to get the stock price index of the day.
Because the base period selected by Hang Seng Stock Index is appropriate, the Hang Seng Stock Index can basically reflect the activity of the whole stock market, whether the stock market is in a big ups and downs or at a normal trading level.
Hang Seng Stock Price Index has been adjusted several times since it was published in 1969. Since the Hong Kong authorities passed legislation in August and 1980 merged the Hong Kong Stock Exchange, the Far East Stock Exchange, the Gold and Silver Stock Exchange and the Kowloon Stock Exchange into the Hong Kong Stock Exchange, at present, only the Hang Seng Stock Index coexists with the newly generated Hong Kong Index, and all other stock indexes in Hong Kong no longer exist.