At a glance
- Provider
- S&P Dow Jones Indices; Averages Committee of 3 S&P DJI and 2 Wall Street Journal representatives[1]
- Launch / base
- Launched and first valued May 26, 1896; base value 40.94[1]
- Constituents
- 30 stocks[1]
- Weighting
- Price-weighted[1]
- Review schedule
- Changes made as needed; no annual or semi-annual reconstitution[1]
- Region
- U.S. companies across all industries except transportation and utilities[2]
Index levels and returns change every trading day and are not shown here. Check the provider's own page for current figures.
Quick answer
The Dow Jones Industrial Average is a price-weighted index of 30 large U.S. companies, maintained by S&P Dow Jones Indices. Higher-priced shares count for more, and a divisor keeps the level continuous through stock splits and member changes [1].
Key points
- The Dow holds just 30 stocks, chosen by a committee rather than by a size cut-off.
- It is price-weighted: a $1 move in any member moves the index by the same amount, whatever the company's size.
- A divisor is adjusted after splits and member changes so the index level stays continuous.
- There is no scheduled reconstitution; members change only when the committee decides.
- Thirty stocks are a narrow sample, so the Dow and broader indexes can move differently on the same day.
#What is the Dow Jones Industrial Average?
The provider describes the Dow as "a 30-stock, price-weighted index that measures the performance of some of the largest U.S. companies" [1]. Investor.gov's glossary lists it among the main U.S. market indices and describes it as 30 "blue chip" stocks [3]. A blue-chip stock is a share in a large, well-established company; see blue-chip stock. The index page adds that it covers all industries except transportation and utilities, which have their own Dow Jones averages [2].
It is also old. The methodology gives May 26, 1896 as both its launch date and first value date [1]. S&P's explainer recalls that the first version simply added up the prices of 12 stocks and divided by 12 [4]. For what an index is in general, start with what a stock market index is.
#How are Dow companies chosen?
There is no formula that automatically admits a company. The Averages Committee, made up of three S&P Dow Jones Indices representatives and two from The Wall Street Journal, chooses members [1]. The methodology says a stock is typically added only if the company has an excellent reputation, shows sustained growth and is of interest to a large number of investors [1]. Companies should be incorporated and headquartered in the U.S., with a plurality of revenue from the U.S. [1].
Because price drives weight, price matters at selection too. The committee monitors whether the highest-priced stock costs more than 10 times the lowest-priced one, and it evaluates share price when considering a company [1].
#What does price-weighted mean?
In a price-weighted index, S&P explains, "constituent weights are determined solely by the prices of the constituent stocks" and shares outstanding are set to a uniform number [5]. In plain terms, the index acts as if you held one share of each company. A company with a $400 share counts ten times as much as one with a $40 share, even if the $40 company is far bigger in total [6].
Worked example
Worked example: the same 10% rise in three different stocks
A toy price-weighted average holds three hypothetical stocks priced at $400, $100 and $40. Divisor = 3, so the starting level is (400 + 100 + 40) ÷ 3 = 180.
- Weights by price (400, 100, 40 out of 540)
- 74.07%, 18.52%, 7.41%
- $400 stock rises 10% → (440 + 100 + 40) ÷ 3
- 193.33 (+7.41%)
- $100 stock rises 10% → (400 + 110 + 40) ÷ 3
- 183.33 (+1.85%)
- $40 stock rises 10% → (400 + 100 + 44) ÷ 3
- 181.33 (+0.74%)
An identical percentage move has ten times the effect when it happens in the $400 stock. Company size plays no part.
Hypothetical prices, calculated in Python. The real Dow divisor is a different number and changes over time.
Price weighting vs cap weighting
Price-weighted (the Dow)
- Weight = share price
- Acts like one share of each company
- A stock split cuts a company's weight
- 30 members picked by committee
Cap-weighted (e.g. the S&P 500)
- Weight = float-adjusted market value
- Bigger companies count for more
- A split does not change weight
- 500 companies under published size rules
#Why does the Dow divisor keep changing?
If the Dow were a plain average, a stock split (when a company swaps each share for several cheaper ones) would knock the index down even though nobody lost money. S&P's explainer says the divisor "is continually being adjusted to preserve historical continuity" after splits, spinoffs and substitutions [4]. The index mathematics guide confirms that price-weighted indexes adjust the divisor for price-affecting corporate actions, including special dividends, splits and rights offerings, and for additions and deletions [5].
Worked example
Worked example: adjusting the divisor after a split
Three stocks trade at $15, $20 and $25. Divisor = 3, so the average is 20. The $20 stock then splits 2-for-1 and trades at $10.
- Before the split: (15 + 20 + 25) ÷ 3
- 20.00
- After the split, old divisor: (15 + 10 + 25) ÷ 3
- 16.67 — a false drop
- New divisor: 50 ÷ 20
- 2.5
- After the split, new divisor: 50 ÷ 2.5
- 20.00 — unchanged
The divisor falls so the average stays at 20. The split stock's weight in the index has halved, because its price halved.
Based on the three-stock illustration in S&P's How The Dow Works guide; figures recalculated in Python.
#How often do Dow members change?
Rarely, and on no fixed calendar. The methodology says changes are made on an as-needed basis and there is no annual or semi-annual reconstitution [1]. Each change is a committee decision, so there is no calendar date on which members are due to be swapped. That makes the Dow different from indexes such as the S&P 500, which are rebalanced every quarter.
| Feature | Dow Jones Industrial Average |
|---|---|
| Members | 30 stocks |
| Weighting | Price-weighted |
| Selection | Averages Committee judgment, not a size rule |
| Sectors excluded | Transportation and utilities |
| Membership changes | As needed; no scheduled reconstitution |
| Price check | Committee watches the highest-to-lowest price ratio (10×) |
Common beginner mistakes
Reading the Dow as "the stock market"
Thirty stocks are a narrow sample of the thousands of listed U.S. companies. A broad index can tell a different story on the same day.
Comparing point moves across eras
A 500-point move means very different things at different index levels. Percentage changes are the fairer comparison.
Assuming the biggest company matters most
In the Dow, the highest share price matters most, not the highest market value. A large company with a low share price can carry little weight.
Thinking a split changes what you own
A split changes the number of shares and the price per share, not the value of the company. The divisor exists precisely so splits do not move the index.
What's the bottom line?
The Dow is a 30-stock, price-weighted average with more than a century of history, held together by a divisor that absorbs splits and member changes. Its design makes high-priced shares matter most, so it is best read alongside broader, cap-weighted measures. For context on tracking indexes with funds, see index funds explained.
Frequently asked questions
Why is the Dow price-weighted?
Its first version simply added up share prices and divided by the number of stocks, and the index is still price-weighted today. Instead of dividing by 30, it now divides by a divisor that is adjusted so splits and member changes do not break the index's history.
Can a company be too expensive for the Dow?
Price is a consideration. The committee monitors whether the highest-priced member costs more than 10 times the lowest and evaluates share price when considering an addition.
Does the Dow include transport and utility companies?
No. It covers all industries except transportation and utilities, which are tracked by the separate Dow Jones Transportation Average and Dow Jones Utility Average.
Is the Dow the same as the S&P 500?
No. The Dow has 30 price-weighted members chosen by committee judgment. The S&P 500 has 500 companies weighted by float-adjusted market value under published eligibility rules.
Sources
Grade A = primary source (regulator, government agency, official rulebook or the index provider's own documents). Numbers in brackets in the text point here.
- S&P Dow Jones Indices. Dow Jones Averages Methodology (May 2026) (2026). Accessed 2026-10-03.A
- S&P Dow Jones Indices. Dow Jones Industrial Average index overview (2026). Accessed 2026-10-03.A
- U.S. SEC — Investor.gov. Market Indices (glossary) (2026). Accessed 2026-10-03.A
- S&P Dow Jones Indices. How The Dow Works (2016). Accessed 2026-10-03.A
- S&P Dow Jones Indices. Index Mathematics Methodology (September 2026) (2026). Accessed 2026-10-03.A
- U.S. SEC — Investor.gov. Index Funds (2026). Accessed 2026-10-03.A
This page is general education, not personal financial, tax or legal advice. Figures in worked examples are hypothetical and calculated before taxes and fees unless stated. Rules and limits change; check the linked primary sources for the current version. How we check every page.
