Ch5. Volume Analysis — The Signal That Confirms a Trend

Overview: Price Can Lie, Volume Can’t

Price can move briefly on light trading. But whether many participants agreed with that move is what volume tells you. Dow Theory’s fifth tenet — “volume confirms the trend” — is exactly this.

Goal of this lesson: Understand the four price-volume relationships and read the substance of supply and demand through breakout validity, volume profile, and OBV.

1. What Volume Means

Volume is the number of shares traded in a period. Rising volume means buying and selling agreed (executed) actively at that level — the size of the market’s interest and energy.

Volume is the fuel of a trend. Like a car running without fuel soon stops, a rally without volume rarely lasts. That’s why you always read price signals alongside volume.

2. The Four Price-Volume Relationships

Price	Volume	Interpretation
Up	Rising	Healthy rise — trend likely to continue
Up	Falling	Weakening momentum — watch for a top
Down	Rising	Strong decline — possible panic selling
Down	Falling	Selling exhausted — possible bottom

Core intuition: when trend direction and volume rise together the trend is healthy; when they diverge, suspect a reversal. A new high on shrinking volume warns that the rally is losing strength.

3. Judging Breakout Validity by Volume

The strongest clue for filtering the false breakouts (whipsaws) from Lesson 4 is volume.

Real breakout: volume surges to 1.5–2× normal as it clears resistance
False breakout: slips past without volume, then snaps back

Resistance breakout:
price  ────┐  /← breakout
           └─┘
volume  ▁▁▁▁█  ← must surge at breakout to be real

A breakout or new high without volume may be a trap or temporary noise. Make “I don’t trust a breakout without volume” a default rule.

4. Volume Profile

Volume profile shows how much volume accumulated at each price level. A price level with heavy volume = a thick node acts as strong support/resistance.

Trading above a thick node → that node acts as support
Trading below a thick node → that node acts as resistance (trapped holders selling at breakeven)

Low-volume gaps tend to be traversed quickly by price.

5. OBV — Accumulating Volume to See Flow

OBV (On Balance Volume) adds the day’s volume on up days and subtracts it on down days, cumulatively.

Close up   → OBV += day's volume
Close down → OBV −= day's volume

Price flat but OBV rising → hidden accumulation → bullish lead signal
Price rising but OBV falling → distribution → bearish warning (divergence)

OBV’s absolute value is meaningless. It’s an indicator of direction and divergence from price. A window into the supply-demand undercurrent that price doesn’t reveal.

Key Takeaways

Volume is the market’s “scale of agreement” with a price move — the fuel of a trend.
Price and volume rising together = healthy trend; divergence suspects a reversal.
A real breakout comes with surging volume — distrust breakouts without it.
Thick volume nodes act as strong support/resistance.
OBV reveals hidden supply/demand through price-volume divergence.

Next lesson: We enter the world of indicators derived from price and volume — RSI and Stochastics for overbought/oversold, MACD and Bollinger Bands for trend and volatility.