Relative strength vs RSI: what is the difference?

Both are called “relative strength”, which causes endless confusion. One compares a stock with other stocks. The other looks only at a stock’s own recent price moves.

Relative strength (comparative)

Compares a stock’s performance with an index or with all other stocks. The scanner’s RS rating ranks stocks 1–99 on weighted returns, and the RS line divides a stock’s price by an index’s price. Both answer: is it beating the market?

RSI (relative strength index)

An oscillator created by J. Welles Wilder, bounded between 0 and 100, calculated from the average gains and losses of a single stock over a period, commonly 14 days. Readings above 70 are often called overbought and below 30 oversold.

Which to use for what

• Finding leaders: relative strength. It picks the stocks outperforming the market.
• Judging short-term stretch: RSI. It shows how fast the stock has moved recently.

They can disagree: a strong leader often stays “overbought” on RSI for a long time.

A caution

Neither predicts the future. Use relative strength to build a shortlist and other tools, plus risk rules, to decide what to do with it.

A worked example

A stock climbs 6% in two weeks and its 14-day RSI reaches 78. A beginner may read “overbought” and sell. A trader who also checks relative strength sees an RS rating of 92 and the stock above a rising 50-day average: a leader. The two indicators measure different things, and in strong uptrends RSI can stay high for weeks.

Strategy examples

These are illustrative rule sets that show how the scanner can be used. They are not recommendations or advice, the numbers are examples, and rules like these can lose money. Test any idea on your own and manage risk before acting.

Leaders with RSI timing

1. Start with relative strength: RS 80 or higher, above a rising 50-day average.
2. Wait for a pullback where RSI falls toward the 40 to 50 zone while price holds the 50-day average.
3. Look for the first day RSI turns up again and price closes higher.
4. Place a stop below the pullback low and size the position from that distance.

Do not sell leaders on RSI alone

1. If RS is high and the trend is intact, treat an RSI above 70 as “strong”, not as a sell signal.
2. Use a trailing stop such as a close below the 20- or 50-day average instead.
3. Review again if RS rating falls below 70 or the price breaks its trend line.

Spot fading leaders

1. Compare price and the RS line: if price makes a new high but the RS line does not, the lead is narrowing.
2. Check RSI for the same signal: a lower RSI peak on a higher price high is a divergence.
3. Treat both together as a caution flag and tighten risk, not as a prediction.

Common mistakes

• Using RSI to pick stocks. RSI cannot tell you whether a stock is beating the market.
• Shorting or selling every “overbought” leader.
• Mixing up the two terms when searching or reading research.
• Changing the RSI period until a past signal fits. Settings tuned to history rarely hold.

Frequently asked questions

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