RSI: The Relative Strength Index

The uses that hold up

• Range trading. In a sideways market with defined boundaries, fading RSI extremes back toward the middle has actual logic behind it, because there is no trend for the extreme to be describing.
• Divergence. Price makes a new high while RSI makes a lower high. Momentum is fading even as price pushes on. Treat it as a warning to tighten management, not as an entry.
• The 50 line as a trend filter. RSI holding above 50 across a pullback says the underlying bias is still bullish. This is a much duller use than 70 and 30, and a far more durable one.
• Failure swings. RSI pulls back from 75 to 58, turns up, but tops at 68 without exceeding 75, then breaks 58. That sequence is the momentum version of a break of structure.

Regime first, indicator second

Every piece of RSI advice flips depending on whether the market is trending or ranging. In a range, an extreme is a fade. In a trend, the same extreme is confirmation. So the honest order of operations is to decide the regime from structure, then pick which RSI reading you are interested in.

Doing it the other way round is how people end up with two contradictory rules and a habit of applying whichever one justifies the trade in front of them. Decide the regime before you look at the oscillator, and write down which rule the regime turns on.

The limits of the oscillator

• It is derived from price. Every oscillator is a rearrangement of data already on the chart. It cannot know anything price does not.
• The 14 setting is a convention. Shorter lookbacks reach extremes constantly, longer ones barely reach them at all. Changing the setting changes what 70 means, so a rule built on a number is really a rule built on a setting.
• It will not tell you how far. RSI at 22 says the recent candles were dominated by selling. It has no opinion about whether the next 200 pips are up or down.
• Divergence can persist. A trend can print three successive bearish divergences and continue. Divergence is evidence of fading momentum, not a dated appointment for a reversal.

An exercise worth doing this week

Open a daily chart and mark every instance where RSI crossed above 70 over the last year. For each one, record what price did over the following ten candles. You will find a cluster where price kept going and a cluster where it turned, and the deciding variable is almost always whether the market was trending or ranging at the time, not the RSI reading itself.

That exercise is worth more than any rule someone hands you, because it produces evidence from the instrument you actually trade. If you want the broader context for why regime matters more than any single tool, the risk management guide covers what a misread regime costs in position-sizing terms.