RSI (Relative Strength Index)

Updated 2026-09-20

Definition

An oscillator from 0 to 100 that measures the speed and size of recent gains relative to losses, usually over 14 periods.

Why it matters

Above 70 is called overbought and below 30 oversold, but in a strong trend it can stay there a long time: it isn't an automatic reversal signal. Useful for divergences.

Practical example

Price makes a new high but the RSI doesn't: divergence, momentum is weakening.

Learn more

Course lesson: Technical indicators: moving averages, RSI, MACD, Bollinger and ATR

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Educational content, not financial advice. Trading involves risk.