RSI Explained: What Overbought and Oversold Actually Mean

The Relative Strength Index is one of the most cited indicators in technical analysis, and one of the most misused. The number printed on a chart tells you about the speed of recent price movement. What it does not tell you is where the price is going, a distinction that matters every time someone says a stock is "overbought" and expects a reversal.

What RSI measures

RSI compares the size of recent gains to the size of recent losses over a rolling window, typically 14 trading sessions. The result is a number between 0 and 100. A stock that has closed higher every day for two weeks approaches 100. A stock that has fallen consistently approaches 0. The math was formalized by J. Welles Wilder Jr. in his 1978 book New Concepts in Technical Trading Systems.

• Above 70: Conventionally called overbought. The stock has gained at a faster rate than average over the window.
• Below 30: Conventionally called oversold. The stock has lost at a faster rate than average.
• Between 40 and 60: Neutral momentum, no clear tilt.

The 70 and 30 levels are conventions, not physical laws. In strong trending markets, RSI can stay above 70 for weeks. In weak markets, it can stay below 30 for extended periods. The label "overbought" describes a data state, not a scheduled event.

How to read RSI in practice

Practitioners use RSI in three broad ways:

• Level signals: Cross above 70 or below 30 as an alert that momentum has reached an extreme. Used alone, this generates many false signals in trending markets.
• Centerline crossovers: A cross above 50 suggests buying pressure is dominating. Below 50 suggests selling pressure. Less prone to whipsaw than the extreme levels.
• RSI divergence: The most studied setup. When price makes a higher high but RSI makes a lower high, momentum is weakening even as the price rises. The reverse is also watched: price at a lower low, RSI at a higher low. Divergence does not guarantee reversal, but it narrows the conditions where one becomes plausible. For more on how divergence between indicators works as a concept, see the signal divergence explainer.

What RSI does not tell you

RSI measures past velocity. It has no information about earnings releases, macro events, or any fundamentals affecting a company. A stock can print RSI 80 and keep climbing for weeks if the catalyst driving it is large and ongoing. A stock at RSI 25 can keep falling if the reason for selling has not been resolved.

RSI also resets with every new window. A 14-session RSI looks at the past 14 sessions, nothing before. A stock that spent three months falling and then had one sharp week of buying can print a high RSI regardless of its longer context.

For further reading on RSI construction, Investopedia maintains a detailed reference: Relative Strength Index (RSI).

RSI as one input among several

Technical analysts rarely use RSI in isolation. It works alongside price structure analysis, volume confirmation, and broader trend context. The EquityBias Bias Score synthesizes momentum signals including RSI-type readings alongside analyst activity, news sentiment, and fundamentals into a single composite. When one dimension disagrees with others, the divergence reading flags the conflict rather than burying it in an average.

You can see today's composite reading for any covered stock in the coverage directory.

EquityBias is a market data research tool. Nothing here is financial advice. RSI levels and readings are descriptive of past price movement, not predictions of future performance.