你以为我不知道你不知道道指是怎么计算出来的吗？

不是专业人士就可以相信亩产万斤吗？

Calculating the Averages

Back in 1896, all Charles Dow needed was a pencil and paper to compute the industrial average. He simply added up the prices of the twelve stocks and then divided by 12. In 1923, the task of working the numbers fell to Arthur "Pop" Harris, who had been hired in 1908 at the age of 22.

In 1896, when Charles Dow scribbled his first simple calculation, no one could have imagined that over the next century his "averages" would become the key benchmark to the nation's economy.

In 1896, when Charles Dow scribbled his first simple calculation, no one could have imagined that over the next century his "averages" would become the key benchmark to the nation's economy. For the next 40 years, Pop calculated the Dow Jones average every hour on the hour for the Dow Jones News Service. On busy trading days, he sometimes bloodied his hands pulling out the ticker tape. Through all those years, the financial world would hold its breath for seven minutes after the New York Stock Exchange's closing bell, waiting for Pop, who was a small, skinny man, to finish his official calculations on a piece of newsprint.

Pop Harris retired in 1963, and by then the advent of computers made it possible to calculate the Dow Jones averages in a fraction of a second any time of the day. Today, the first step in calculating The Dow is still totaling the prices of the component stocks. But the rest of the math isn't so easy anymore, because the divisor is continually being adjusted. The reason? To preserve historical continuity. In the past hundred-plus years, there have been many stock splits, spinoffs and stock substitutions that, without adjustment, would distort the value of the Dow. To understand how the formula works, consider a stock split. Say three stocks are trading at $15, $20 and $25; the average of the three is $20. But if the company with the $20 stock has a two-for-one split, its shares suddenly are priced at half of their previous level. That's not to say the value of the investment has changed; rather, the $20 stock simply sells for $10, with twice as many shares available. The average of the three stocks, meanwhile, falls to $16.66. So, The Dow divisor is adjusted to keep the average at $20 and reflect the continuing value of the investment represented by the gauge.

Over time, the divisor has been adjusted several times, mostly downward (it stood at 0.125552709 at the end of 2008), which means that it has become, in effect, a multiplier. This explains why the average can be reported as, say, 9800, even though the sum of all 30 stock prices is nowhere close to that number. A one-point move in any component stock pushed the average up or down almost eight points at the end of 2008.

"What the divisor does is keep things level with history" says Robert Dickey, a technical stock analyst at Minneapolis-based Dain Rauscher Inc. Current divisors for each of the Dow Jones averages appear on page C4 of The Wall Street Journal every day.

In another effort to preserve continuity, the guardians of the Dow, The Wall Street Journal editors, keep to a minimum any changes in the index's component stocks. Most substitutions have arisen because of mergers. From time to time, changes also are made to keep The Dow representative of the broad market, which itself shifts in composition.

As the economy has moved from railroads to heavy industry to consumer goods to technology over the past century, the Dow's component stocks have reflected those changes. Yesteryear's components, such as Bethlehem Steel Corp., Westinghouse Electric Corp. and Woolworth Corp., have given way to Hewlett-Packard Co., Johnson & Johnson, Microsoft Corp. and Wal-Mart Stores Inc.

Since Charles Dow's time, several stock-market indices have challenged the Dow Jones Industrial Average. In 1926, Standard Statistics Co., a predecessor of today's Standard & Poor's Corp., developed a 90-stock index that by the 1950s had evolved into the S&P 500, a benchmark widely used today by professional money managers. Today, there are thousands of indices, tracking everything from broad markets to tiny slivers to investment strategies.
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How The Dow Jones Industrial Average is Calculated

By JLP | December 4, 2006

 

Have you ever wondered HOW the Dow Jones Industrial Average is calculated? Here’s how!

According to the Dow Jones website, the index is calculated as follows:

The Dow Jones averages are unique in that they are price weighted rather than market capitalization weighted. Their component weightings are therefore affected only by changes in the stocks’ prices, in contrast with other indexes’ weightings that are affected by both price changes and changes in the number of shares outstanding.

When the averages were initially created, their values were calculated by simply adding up the component stocks’ prices and dividing by the number of components. Later, the practice of adjusting the divisor was initiated to smooth out the effects of stock splits and other corporate actions.

According to this weekend’s Barron’s, the current divisors are:

Dow Jones 30 Industrial Average: .12482483
Dow Jones 20 Transportation Average: .20882618
Dow Jones 15 Utilities Average: 1.4646169
Dow Jones 65 Composite Average: .77093357

So, to illustrate the calculation of the Dow Jones Industrial Average, look at the following table:

Ticker Symbol	Current Price (12/02/2006)
AA	30.87
AIG	69.77
AXP	58.55
BA	89.55
C	49.38
CAT	61.19
DD	46.45
DIS	33.09
GE	35.28
GM	29.69
HD	38.97
HON	42.81
HPQ	39.44
IBM	91.25
INTC	20.93
JNJ	65.97
JPM	46.01
KO	46.57
MCD	42.08
MMM	79.98
MO	84
MRK	45.06
MSFT	29.12
PFE	27.86
PG	62.69
T	34
UTX	63.86
VZ	34.64
WMT	45.87
XOM	77.2
TOTAL OF ALL PRICES	1522.13
CURRENT DIVISOR	.12482483
DIVIDE TOTAL BY DIVISOR	12194.13

Pretty cool isn’t it?

You can also calculate how much a particular stock is going to affect the average. For instance, today Pfizer is down 3.19 (at this writing). To find out what kind of impact that particular stock will have on the Average, you simply divide the price change by the divisor (-3.19 ÷ .12482483 = -25.56). So, Pfizer is taking away 25.56 points from the Dow Jones Industrial Average so far today. Fortunately, the rest of the components are doing okay, as the Dow is up around 95 points right now.

Now go tell all your friends and family that JLP taught you something interesting today!

Other cool stuff:

History of the Dow Jones Industrial Average components (pdf)

The Chicago Board of Trade on the Dow Divisor.

- See more at: http://allfinancialmatters.com/2006/12/04/how-the-dow-jones-industrial-average-is-calculated/#sthash.SYsxGhXE.dpuf

How The Dow Jones Industrial Average is Calculated

By JLP | December 4, 2006

 

Have you ever wondered HOW the Dow Jones Industrial Average is calculated? Here’s how!

According to the Dow Jones website, the index is calculated as follows:

The Dow Jones averages are unique in that they are price weighted rather than market capitalization weighted. Their component weightings are therefore affected only by changes in the stocks’ prices, in contrast with other indexes’ weightings that are affected by both price changes and changes in the number of shares outstanding.

When the averages were initially created, their values were calculated by simply adding up the component stocks’ prices and dividing by the number of components. Later, the practice of adjusting the divisor was initiated to smooth out the effects of stock splits and other corporate actions.

According to this weekend’s Barron’s, the current divisors are:

Dow Jones 30 Industrial Average: .12482483
Dow Jones 20 Transportation Average: .20882618
Dow Jones 15 Utilities Average: 1.4646169
Dow Jones 65 Composite Average: .77093357

So, to illustrate the calculation of the Dow Jones Industrial Average, look at the following table:

Ticker Symbol	Current Price (12/02/2006)
AA	30.87
AIG	69.77
AXP	58.55
BA	89.55
C	49.38
CAT	61.19
DD	46.45
DIS	33.09
GE	35.28
GM	29.69
HD	38.97
HON	42.81
HPQ	39.44
IBM	91.25
INTC	20.93
JNJ	65.97
JPM	46.01
KO	46.57
MCD	42.08
MMM	79.98
MO	84
MRK	45.06
MSFT	29.12
PFE	27.86
PG	62.69
T	34
UTX	63.86
VZ	34.64
WMT	45.87
XOM	77.2
TOTAL OF ALL PRICES	1522.13
CURRENT DIVISOR	.12482483
DIVIDE TOTAL BY DIVISOR	12194.13

Pretty cool isn’t it?

You can also calculate how much a particular stock is going to affect the average. For instance, today Pfizer is down 3.19 (at this writing). To find out what kind of impact that particular stock will have on the Average, you simply divide the price change by the divisor (-3.19 ÷ .12482483 = -25.56). So, Pfizer is taking away 25.56 points from the Dow Jones Industrial Average so far today. Fortunately, the rest of the components are doing okay, as the Dow is up around 95 points right now.

Now go tell all your friends and family that JLP taught you something interesting today!

Other cool stuff:

History of the Dow Jones Industrial Average components (pdf)

The Chicago Board of Trade on the Dow Divisor.

- See more at: http://allfinancialmatters.com/2006/12/04/how-the-dow-jones-industrial-average-is-calculated/#sthash.SYsxGhXE.dpuf

 

How The Dow Jones Industrial Average is Calculated

By JLP | December 4, 2006

 

Have you ever wondered HOW the Dow Jones Industrial Average is calculated? Here’s how!

According to the Dow Jones website, the index is calculated as follows:

The Dow Jones averages are unique in that they are price weighted rather than market capitalization weighted. Their component weightings are therefore affected only by changes in the stocks’ prices, in contrast with other indexes’ weightings that are affected by both price changes and changes in the number of shares outstanding.

When the averages were initially created, their values were calculated by simply adding up the component stocks’ prices and dividing by the number of components. Later, the practice of adjusting the divisor was initiated to smooth out the effects of stock splits and other corporate actions.

According to this weekend’s Barron’s, the current divisors are:

Dow Jones 30 Industrial Average: .12482483
Dow Jones 20 Transportation Average: .20882618
Dow Jones 15 Utilities Average: 1.4646169
Dow Jones 65 Composite Average: .77093357

So, to illustrate the calculation of the Dow Jones Industrial Average, look at the following table:

Ticker Symbol	Current Price (12/02/2006)
AA	30.87
AIG	69.77
AXP	58.55
BA	89.55
C	49.38
CAT	61.19
DD	46.45
DIS	33.09
GE	35.28
GM	29.69
HD	38.97
HON	42.81
HPQ	39.44
IBM	91.25
INTC	20.93
JNJ	65.97
JPM	46.01
KO	46.57
MCD	42.08
MMM	79.98
MO	84
MRK	45.06
MSFT	29.12
PFE	27.86
PG	62.69
T	34
UTX	63.86
VZ	34.64
WMT	45.87
XOM	77.2
TOTAL OF ALL PRICES	1522.13
CURRENT DIVISOR	.12482483
DIVIDE TOTAL BY DIVISOR	12194.13

Pretty cool isn’t it?

You can also calculate how much a particular stock is going to affect the average. For instance, today Pfizer is down 3.19 (at this writing). To find out what kind of impact that particular stock will have on the Average, you simply divide the price change by the divisor (-3.19 ÷ .12482483 = -25.56). So, Pfizer is taking away 25.56 points from the Dow Jones Industrial Average so far today. Fortunately, the rest of the components are doing okay, as the Dow is up around 95 points right now.

Now go tell all your friends and family that JLP taught you something interesting today!

Other cool stuff:

History of the Dow Jones Industrial Average components (pdf)

The Chicago Board of Trade on the Dow Divisor.

- See more at: http://allfinancialmatters.com/2006/12/04/how-the-dow-jones-industrial-average-is-calculated/#sthash.SYsxGhXE.dpuf