The stochastic oscillator is a momentum tool that measures where price closed relative to its recent range. It's popular for spotting overbought and oversold conditions — with the same big caveat as every oscillator.
What it measures
The stochastic compares the latest close to the high-low range over a set period (usually 14), scaled 0–100, with two lines:
- %K — the main line.
- %D — a moving average of %K (the signal line).
The idea: in an uptrend, prices tend to close near their highs; in a downtrend, near their lows.
How traders read it
- Above 80 — "overbought"; below 20 — "oversold".
- Crossovers — %K crossing %D can flag a momentum shift.
- Divergence — price makes a new extreme but the stochastic doesn't, hinting at exhaustion (see divergence trading).
The trap
Just like RSI, "overbought" doesn't mean sell. In a strong trend the stochastic can stay pinned at an extreme for ages while price keeps running. Selling every overbought reading in an uptrend is a fast way to lose.
Using it well
Use the stochastic for context and confirmation, not as a standalone trigger. It works best in ranging markets and at clear support/resistance. Always define risk with a stop and the risk/reward calculator.
The stochastic describes momentum within a range. The trend decides whether an extreme reading means anything.
Education only — not financial advice.