An oscillator converts price into a bounded number — usually 0 to 100 — that describes how fast and how persistently price has been moving. It answers “how hard is this move pushing?”, never “which way will it go next?”
RSI, properly understood
The Relative Strength Index compares the size of recent gains to the size of recent losses over a lookback period, conventionally 14. If every one of the last 14 periods closed up, RSI reads 100. If all closed down, it reads 0.
The traditional interpretation says above 70 is “overbought” and below 30 is “oversold.” This is where enormous amounts of money have been lost.
A far more useful way to read RSI is by where it finds its floor and ceiling:
| RSI behaviour | What it indicates |
|---|---|
| Holds 40–80 range, bottoms near 40 | Healthy uptrend — pullbacks are being bought |
| Holds 20–60 range, tops near 60 | Healthy downtrend — rallies are being sold |
| Repeatedly fails to exceed 60 in an uptrend | Momentum deteriorating beneath the price |
| Oscillates 30–70 with no persistence | Ranging market — mean-reversion conditions |
MACD
MACD measures the distance between two exponential moving averages, typically the 12 and 26 period, plotted as a line. A 9-period average of that line is the signal line, and the histogram shows the gap between the two.
Because it is built from moving averages, MACD inherits their lag. Its real value is not the crossover — it is the histogram's rate of change. A histogram that is still positive but shrinking tells you the trend is decelerating while price is still rising. That is genuinely early information.
Divergence
Divergence occurs when price and the oscillator disagree:
- Bearish divergence — price makes a higher high, the oscillator makes a lower high. The new high was achieved with less force than the previous one.
- Bullish divergence — price makes a lower low, the oscillator makes a higher low. The decline is losing conviction.
Divergence is a legitimate warning that a move is tiring. It is also one of the most over-traded concepts in retail trading, for one reason: divergence can persist for a very long time. A strong trend routinely produces three or four consecutive divergences before anything happens, and each one takes out the traders who acted on it.
Why stacking oscillators fails
RSI, stochastics, CCI, Williams %R and momentum are all computed from the same underlying price series using similar arithmetic. Adding all five does not give you five independent opinions — it gives you one opinion, repeated, which feels like confirmation.
If you want genuinely independent inputs, combine categories that measure different things: one momentum reading, one trend reading, one volume reading, and the price structure itself.