The relative strength index (RSI)

The relative strength index (RSI) is a momentum indicator used in technical analysis. RSI measures the speed and magnitude of a security's recent price changes to detect overbought or oversold conditions in the price of that security.

The RSI is helpful for market participants in identifying trends. In a strong uptrend, the RSI typically stays between 40 and 90, with the 40-50 range acting as support. In a strong downtrend, the RSI ranges from 10 to 60, with the 50-60 range serving as resistance.