Indicators, and what the readings mean

MACD: three components, two crossovers, and the divergence trap

MACD looks like three indicators and is really one subtraction. Once you see which subtraction, every reading on it becomes readable - including the readings that mean nothing.

About 11 minutes to read. Free, no account.

The three components

MACD stands for moving average convergence divergence, which is an unhelpful name for a simple idea: measure how far apart two moving averages are. The conventional settings are 12, 26 and 9.

All three definitions

MACD line  =  EMA(12)  -  EMA(26)
signal     =  EMA(9) of the MACD line
histogram  =  MACD line  -  signal

Read those again slowly, because everything else follows from them. The MACD line is a difference between two averages, so it measures separation. The signal line is an average of that difference, so it measures where the separation has been. The histogram is the gap between the two, so it measures whether the separation is growing or shrinking.

A worked reading

EMA(12)    =  104.00
EMA(26)    =  102.50
MACD line  =  104.00 - 102.50  =  +1.50
signal     =  +1.10            (its own 9-period EMA)
histogram  =  1.50 - 1.10      =  +0.40

The MACD line against its signal line, with the histogram underneath. The histogram is nothing but the vertical distance between the two lines, so it crosses zero at exactly the moment they cross each other.

The reading is in price units, which trips everyone up

Because the MACD line is a subtraction of two prices, it is denominated in the coin’s price. A coin trading near 60,000 can have a MACD reading in the hundreds. A coin trading at 0.0024 has one in the millionths. The numbers are not comparable across coins, and they are not even comparable for the same coin before and after a large move in price level.

If you want to compare, divide by price to put it in percent:

Normalising a reading

MACD line / price  =  1.50 / 104.00  =  1.44%

which says: the fast average sits 1.44% above the slow one

That version is readable and comparable. "MACD is at 1.5" is not a sentence about anything until you know what price it was divided into.

Two different crossovers, two different meanings

People say "MACD crossed" to mean either of two things, and they are not the same event.

The zero-line cross. MACD crossing zero means EMA(12) has crossed EMA(26) - nothing more. It is the ordinary moving-average cross from the moving averages lesson, with the same arithmetic lag. It is the slower and the more meaningful of the two.
The signal-line cross. MACD crossing its own 9-period average means the separation between the two EMAs has turned relative to where that separation has recently been. That is a statement about the rate of change of a rate of change - which is why it is quick, and why it is the noisiest thing on the indicator.

In a trending market the signal-line cross is a reasonable way of noticing that a pullback has stopped getting worse. In a range it fires in both directions every few bars and carries no information whatsoever. The indicator cannot tell you which market you are in; the zero line and the slope of the averages can.

The histogram is the only early part, and it is noisy

The histogram shrinks before the lines cross, by definition - it is their distance, so it must reach zero at the crossing. Shrinking bars while price is still making new highs mean the two averages have stopped separating: the advance is no longer accelerating.

That is genuinely information, and it is weaker than it feels. "Stopped accelerating" is the normal condition of most advances most of the time - a trend that gained 3% a day and now gains 1% a day is still a trend. Treat a shrinking histogram as a reason to pay attention, never as a reason to act.

Divergence, and the trap inside it

MACD divergence is the same construction as RSI divergence: price makes a higher high, MACD makes a lower high. It means the second push opened a smaller gap between the averages than the first one did. The honest reading is "this leg had less momentum behind it than the last leg", and that is all.

The trap has nothing to do with MACD and everything to do with how the pattern is found. A divergence is a comparison between two pivots that you choose. Change which high you compare and the divergence appears or disappears. And a pivot can only be identified after price has left it, so the pattern is always complete in hindsight and never complete in the moment you would need it.

This is the general skill, and it is worth more than any indicator in the school: separate what is on the chart from what you noticed because you already knew the ending.

The settings, and why 12-26-9 is not sacred

The defaults come from an era of hand-drawn daily stock charts, where 12 and 26 bars were roughly two and four weeks of trading days and 9 was about two weeks. Crypto trades continuously, seven days a week, so those spans no longer line up with anything in the calendar.

That is an argument for knowing what the numbers mean, not an argument for hunting better ones. Testing many combinations on the chart in front of you and keeping the best is the curve fitting the moving-averages lesson warns about. Faster settings cross more often; slower settings cross later. There is no setting that makes a lagging indicator lead.

Reading MACD next to a signal

Used as context it answers one question well: is the separation between fast and slow money widening or narrowing right now? That frames whether you are reading a trade into an accelerating move or a decelerating one.

What it must not do is move your stop. A signal’s stop is a price and a rule decided before the trade existed; a bullish-looking histogram is not evidence about that price. Re-reading an indicator to justify staying in a losing trade is the most expensive habit in retail trading, and MACD - with three components and two crossovers - offers an unusually rich supply of excuses. See the risk disclaimer.

The terms, defined

MACD line: EMA(12) minus EMA(26). The distance between a fast and a slow average, in the price units of whatever you are charting.
Signal line: A 9-period EMA of the MACD line - an average of a difference.
Histogram: MACD line minus signal line. It reaches zero exactly when the two lines cross, and its height is their distance.
Zero-line cross: MACD passing through zero, which is identically EMA(12) crossing EMA(26). The slower, more meaningful crossover.
Signal-line cross: MACD crossing its own 9-period average. Quick, and the noisiest reading on the indicator.
Normalised MACD: The MACD line divided by price, expressed as a percent, so that readings can be compared between coins and across price levels.

What this means in practice

Say the subtraction out loud before reading anything: the line is fast minus slow, the signal is an average of that, the histogram is the gap.
Divide by price before comparing MACD between two coins - the raw number is in price units.
Distinguish the two crossovers. The zero-line cross is the moving-average cross; the signal-line cross is a much faster and much noisier thing.
Let a shrinking histogram make you attentive, not active.
Only count a divergence you could have drawn with the right-hand side of the chart covered.
Never let any of the three components move a stop that was set before the trade began.

Nothing in this lesson is financial advice or an instruction to trade. See the risk disclaimer. We never recommend a leverage setting - that decision is yours.