Relative Strength: Comparing Performance (Not the Same as RSI)
Relative strength measures whether an asset is stronger or weaker than another asset or the broader market — completely different from the RSI indicator. How to use it to filter opportunities and why it helps in rotation strategies.
Many people confuse "relative strength" with the RSI indicator, but they're entirely different things. RSI (the Relative Strength Index) measures the momentum of one asset against its own price history. Relative strength, on the other hand, compares an asset's performance against another asset or the broader market. Getting this distinction right lets you use a very practical analysis tool.
What relative strength is
At its core, relative strength is just a comparison: take asset A's performance and divide it by asset B's performance (or by an index representing the market). The result is a "ratio line."
- If this line is rising, asset A is stronger than B — it's rising faster or falling slower.
- If this line is falling, asset A is weaker than B.
The nice part is that it's independent of whether the absolute price is up or down. A stock can be falling, but if it's falling less than the broad market, its relative strength is still rising — a sign it's holding up well.
Why investors care
- It filters the leaders. In an uptrend, assets with high relative strength are often the ones leading the flow of money. In a downtrend, relatively weak assets tend to fall harder.
- Fair comparison in context. Is a 10% return good or bad? It depends on the broad market. Relative strength puts performance in context, instead of judging a number in isolation.
- It supports rotation strategies. Many trend-following approaches favor holding what's relatively strong and avoiding what's relatively weak.
Basic use
- Choose an appropriate benchmark — a market index, a sector, or another asset you're considering.
- Watch the direction of the ratio line, not just the asset's own price.
- Favor groups with improving relative strength, and be wary of groups weakening against the market, even if the absolute price is still rising.
Things to keep in mind
Relative strength tells you who's stronger than whom, but not why or at what valuation. A relatively strong asset can still be too expensive; a relatively weak one isn't necessarily a "buy the dip" opportunity. It's also lagging: by the time a strength trend is very clear, much of the move may have already happened.
So treat relative strength as a supplementary filter, not a standalone buy/sell signal. Combining it with trend analysis, valuation, and risk management gives a far fuller picture than looking at one asset's price in a vacuum.