Relative Strength

August 24, 2024 Trading

Comparative price performance of one security, portfolio, or market against a benchmark or peer over the same period.

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Relative strength compares the price performance of one security, portfolio, or market with a benchmark or peer over the same period. An asset has positive relative strength when it outperforms the comparison, even if both prices are falling.

Relative strength is not the same as the Relative Strength Index (RSI). RSI is a bounded oscillator calculated from one asset’s recent gains and losses.

Key Takeaways

Relative strength answers a comparative question: which asset performed better?
The benchmark, currency, timeframe, and return definition must be stated.
A rising relative-strength line can occur while the asset’s absolute price declines.
Relative outperformance does not establish positive return, low risk, or fair value.
Benchmark selection can materially change the conclusion.

Relative-Strength Ratio

A simple price-relative line divides the asset price by the benchmark level:

RS_t = \frac{P_{asset,t}}{P_{benchmark,t}}

If the ratio rises, the asset is outperforming the benchmark over that interval. If it falls, the asset is underperforming. Analysts often normalize the starting ratio to 100 to make changes easier to read.

For return comparisons, an analyst may instead compare total returns directly. Price-only comparisons can understate performance when dividends or other distributions differ.

Choosing the Benchmark

Comparison	Useful for	Main caution
Broad market index	Evaluating market-relative performance	Sector exposure may drive the difference
Sector or industry index	Comparing similar businesses	The index may be concentrated or constructed differently
Peer security	Pairwise company comparison	Company-specific events can dominate
Portfolio benchmark	Evaluating a mandate or strategy	Benchmark must match the portfolio’s investable universe and risk
Currency-adjusted benchmark	Cross-border comparison	FX translation and hedging treatment must be consistent

A benchmark chosen after seeing the result can make ordinary performance appear exceptional. The comparison should be selected before evaluation and remain economically relevant.

Relative Strength vs. RSI

Feature	Relative strength	RSI
Inputs	Asset and benchmark prices or returns	One asset’s recent gains and losses
Output	Ratio, normalized line, or relative return	Oscillator between `0` and `100`
Main use	Identify outperformance or underperformance	Evaluate recent momentum conditions
Common mistake	Treating outperformance as positive return	Treating a threshold as an automatic reversal signal

How It Is Used

Rank securities or sectors by recent comparative performance.
Check whether a portfolio holding is adding value relative to its benchmark.
Confirm whether a price breakout is also outperforming the broader market.
Build momentum or factor portfolios from prior relative returns.
Compare defensive behavior during a broad decline.

These uses still require liquidity, concentration, turnover, and valuation review. A security can rank highly on relative strength immediately before a sharp reversal.

Risks and Limitations

Benchmark risk: an inappropriate comparison produces a misleading conclusion.
Price-only bias: ignoring dividends, fees, and currency effects can distort performance.
Concentration risk: apparent strength may come from one industry or market factor.
Reversal risk: recent winners can change direction quickly.
Selection bias: changing the lookback or peer group after the fact can manufacture outperformance.
Execution risk: a ranking based on closing prices may not reflect achievable trade prices.

This page is educational only. Relative strength is not a recommendation or personalized investment, trading, legal, tax, or regulatory advice.

Sources and Further Reading

FAQs

Can a falling stock show relative strength?

Yes. If it falls less than the selected benchmark over the same period, it has outperformed even though its absolute return is negative.

Is relative strength the same as RSI?

No. Relative strength compares an asset with a benchmark. RSI uses one asset’s recent average gains and losses to produce an oscillator from 0 to 100.

Momentum: Rate and persistence of price change over a selected interval.
Relative Strength Index: Oscillator based on recent gains and losses.
Momentum Investing: Strategy that ranks assets using prior performance.
Market Trend: Directional structure of an asset or market.
Divergence: Disagreement between price and an indicator or comparative line.

Money Flow Index

RSI