Who this entry is for — Readers who encounter the “six tenets of Dow Theory” and want to distinguish Charles Dow's original contribution from the later systematisation.
Dow Theory is a tradition for reading stock averages and market movements. It derives from the editorials of Charles H. Dow, but the form known today was constructed after his death by S. A. Nelson, William Peter Hamilton and Robert Rhea.
Dow did not publish a book titled Dow Theory and did not leave a canonical list of six principles. Nelson collected some of the editorials in The A B C of Stock Speculation (1903); Hamilton developed the method in The Stock Market Barometer (1922); Rhea arranged it in The Dow Theory (1932).
Historically documented propositions
In plain language — The theory observes the market through aggregate averages, distinguishes movements at different scales, and requires confirmation before assigning significance to a signal.
| Proposition | Source and scope |
|---|---|
| The market contains several simultaneous movements | Dow, in the editorials collected by Nelson; Hamilton refines their hierarchy |
| An average is more informative than an individual stock | Nelson and Hamilton use averages to represent the general market |
| The two averages must corroborate each other | Hamilton applies the principle to industrials and railroads |
| A prolonged narrow range forms a “line” | Hamilton: it may resolve as accumulation or distribution |
| A primary movement is recognised through a sequence of highs and lows | Hamilton describes turns and continuations through the averages |
| Prices and averages incorporate dispersed knowledge and expectations | Hamilton's explicit formulation of the market as a barometer |
These propositions are not an algorithm. Words such as “trend”, “confirmation” and “line” require judgement about the period under observation and the joint behaviour of the averages.
The modern “six tenets”
Many contemporary manuals present a list similar to this:
- the market discounts everything;
- there are three degrees of trend;
- the primary trend passes through several phases;
- the averages must confirm each other;
- volume confirms the trend;
- a trend remains valid until a reversal signal appears.
The list is useful as a teaching summary, but it is not a document signed by Dow. It combines ideas from the editorials with formulations by Hamilton, Rhea and later textbooks.
The case of volume is particularly revealing. Hamilton observes that activity tends to expand in bull markets and contract in bear markets, but also warns that volume is relative and “far less significant” than commonly believed. In his treatment, confirmation between the averages has a more defined role than a simple increase or decrease in volume.
How the theory is read
1. Establish the scale
The same session may rise within a bearish secondary reaction that is itself inside a bullish primary movement. Before assigning a signal, the analyst must therefore specify which of the three movements is being examined.
2. Observe the aggregate market
Dow and Hamilton do not treat the behaviour of an individual stock as evidence about the general market. The averages reduce the effect of news, manipulation, or anomalies specific to one company.
3. Seek corroboration
In Hamilton's formulation, the industrial and railroad averages may turn on different dates; what matters is that they ultimately take the same direction. A non-confirmation suspends or weakens the interpretation, but does not by itself create a contrary signal.
4. Recognise the limits
The barometer does not predict the duration, magnitude, or exact turning point of a movement. Hamilton compares reading the averages to using an instrument that requires skill: a reading may be withdrawn or corrected by subsequent behaviour.
Historical validity and empirical testing
Dow Theory arose from price-weighted US averages in an economy where railroads and industry had a central relationship. Applying it today to sectors, ETFs, futures, or cryptocurrencies requires choices that are not contained in the original sources.
Its performance is not assessed uniformly either. Alfred Cowles (1934) interpreted Hamilton's calls unfavourably relative to buy-and-hold. Brown, Goetzmann and Kumar (1998) re-examined the same editorials and found more favourable risk-adjusted results. The disagreement shows how strongly the retrospective coding of discretionary commentary depends on the rules selected by the researcher.
Operational limit — A historical reconstruction does not demonstrate that a modern version of Dow Theory will produce future returns. Markets, indexes, costs and confirmation criteria must be defined and tested separately.
Sources
- S. A. Nelson, The A B C of Stock Speculation, 1903, chs. V–IX, Internet Archive.
- William Peter Hamilton, The Stock Market Barometer, Harper & Brothers, 1922, chs. I, III, XIII and XV, Internet Archive.
- Robert Rhea, The Dow Theory, Barron's, 1932, Open Library.
- Brown, Goetzmann and Kumar, “The Dow Theory: William Peter Hamilton's Track Record Reconsidered”, The Journal of Finance 53(4), 1998, doi:10.1111/0022-1082.00054.