Trader Vic Ch. 2: Defining a Trend — Dow Theory's Three Movements and Why Definition Precedes Signal

Investment Background

"Follow the trend" is the most repeated sentence in trading.

It is also the emptiest, unless "trend" is defined.

Consider how serious this is. If a trend is undefined:

• "The trend is intact" and "the trend has ended" become subjective judgments.
• And subjective judgment, while losing, drifts automatically toward "the trend is intact, I just need to wait."

An undefined notion of trend is not a tool. It is a device for rationalizing a refusal to cut losses.

Sperandeo's method starts from Charles Dow, and Dow Theory's core contribution is precisely that it splits "trend" into three objects with distinct durations.

The Wall Street Translation

The Three Movements

Dow Theory holds that three movements exist in a market simultaneously:

Movement	Typical duration	Analogy	Who should care
Primary movement (primary trend)	Months to years	The tide	Long-term investors, retirement portfolios
Secondary movement (reaction)	Weeks to months	Waves	Swing traders
Daily fluctuation	Days	Ripples	Day traders, market makers

The practical value of this taxonomy is that it makes "has the trend changed" answerable — provided you first state which one you are asking about.

A 10% decline may be entirely irrelevant to the primary trend (merely a secondary reaction) while being decisive for the secondary trend.

Most investors' error is using daily-fluctuation information to make primary-trend decisions.

This deserves expansion, because it is the chapter's most direct value to a retirement investor.

A Concrete Application

Suppose the market falls 12% over three weeks.

If you are watching daily fluctuations, you see continuous red and lose money every day. That vantage point generates an urge to act.

If you are watching the primary trend, your question is entirely different: did this decline damage the structure of the primary trend?

And "the structure of the primary trend" can be defined — which is Chapter 3. In Dow's and Sperandeo's framework, a rising primary trend consists of a series of higher highs and higher lows.

So the question becomes a checkable factual one: did this decline break the prior significant low?

• Not broken → the primary trend structure is intact; this is a secondary reaction.
• Broken → this is the first evidence the trend may be changing (but not yet confirmation — Chapter 3 explains why).

Note what has changed: from "I feel like the market is terrible" to "the prior low was 4,200; we are at 4,300; it has not broken."

The first cannot be tested. The second can. That is the entire function of a definition.

Dow Theory's Other Principles

Sperandeo retains several of Dow's core principles, three of which remain useful to a modern investor.

One: a trend persists until a clear reversal signal appears.

This is a rule about the burden of proof. The default assumption is continuation, and overturning it requires evidence. This prevents you from revising your judgment on every small fluctuation.

Two: volume should confirm the trend.

In an uptrend, volume on advancing days should exceed volume on declining days. If price rises while volume contracts, that is a warning — the advance lacks participation.

This overlaps in what it observes with the Accumulation/Distribution Rating in How to Make Money in Stocks, but the use differs: O'Neil uses it to select individual stocks; here it judges the health of the overall trend.

Three: two indices should confirm one another.

Dow's original version required the Industrials and the Rails to move together. The modern equivalent is checking whether different sectors or indices are in sync — for instance, whether small caps and credit markets follow when the large-cap index makes a new high.

If only a handful of stocks are driving the index higher, the trend rests on a narrow base.

Three Limits That Must Be Stated Honestly

The technical analysis content in this book requires honest bounding, or it genuinely conflicts with our site's position.

One, Dow Theory lags. It confirms a change only after the trend has already changed. It never catches tops or bottoms — that is not a flaw but its design. Any use claiming to anticipate turns misapplies it.

Two, the academic evidence is unfriendly to technical analysis generally. Chapter 1 of A Random Walk Down Wall Street in this library calls technical analysis astrology outright, and gives reasons. We do not paper over this conflict.

This book's position in the library must therefore be precise: it is not included as "a method that beats the market," but as a language for defining market state. The definitions are useful even if trading systems built on them do not produce excess returns.

Three, trend identification is always clear in hindsight and always murky in the moment. On any historical chart the turning points are obvious. At the right-hand edge, where you actually decide, it never is.

Executable Trading Rules

1. Before making any judgment, state which movement you are discussing. This is the chapter's most valuable discipline. "The market is going to fall" cannot be discussed. "The primary trend may be turning because the prior low broke" can be tested.

2. For a retirement portfolio, watch only the primary movement, and watch it infrequently. Concretely: once a quarter is sufficient. Daily fluctuation is pure noise to a thirty-year portfolio, and the only consequence of observing noise is the urge to trade.

3. Apply "a trend persists until falsified" to your holdings. The retirement version: your allocation plan remains valid until your life circumstances change — not until the market makes you uncomfortable. The burden of proof sits on the side of change.

4. Use breadth to check market health. If the index makes new highs while the number of stocks making new highs shrinks, the base is narrowing. This observation requires no trading, but it means a correction will not surprise you.

5. Never use daily-fluctuation information for long-term decisions. Directly executable: delete the price alerts on your phone. The Psychology of Money and Trading in the Zone reach the same conclusion — the higher the observation frequency, the worse the decision quality.

Relevance to a Retirement Portfolio

This chapter remains useful to someone who never trades, in a specific way.

It supplies a framework for not panicking.

During a violent decline, the most damaging psychological state is "I do not know what this is." That uncertainty drives selling.

With a definition, you can ask a concrete question: has the primary trend structure been broken?

When the answer is yes, your plan should already contain a response (rebalancing, drawing on the cash buffer).

When the answer is no, you have a grounded reason for inaction.

In either case you are not deciding on feeling. That is the entire value.

To restate: this is not advice to move in and out of the market based on trend. The evidence in this library — Sharpe's arithmetic, SPIVA persistence data, and the market-structure argument in Winning the Loser's Game — all points the same way: timing is negative-value for the overwhelming majority of investors.

This chapter gives you a language for understanding, not a license to act.

Chapter 3 delivers Sperandeo's most concrete and most distinctive contribution: a three-step mechanical rule for judging that a trend has changed.