RSI Is a Speedometer, Not a Compass

When you press the accelerator in a car and touch 100 km/h, your speedometer reveals exactly one fact: you are travelling fast. It cannot tell you whether you are heading toward Bengaluru or driving straight toward a ditch.

Many retail investors treat the Relative Strength Index (RSI) like a directional compass. When the line crosses above 70, they assume the stock has become "overbought" and must fall. When it dips below 30, they assume it is "oversold" and must bounce. But RSI does not measure whether a stock is cheap or expensive. It measures velocity—the speed and consistency of recent price changes.

What RSI Actually Calculates

Created by J. Welles Wilder, the RSI compresses 14 sessions of price action into an oscillating scale from 0 to 100. It looks at the average point gain on green days versus the average point loss on red days.

Here is how that calculation plays out on paper over a standard 14-day window for an illustrative stock.

Notice what an RSI of 71.43 means: on average, buyers pushed the stock up two-and-a-half times faster than sellers pulled it down. That is a measurement of intense upward velocity, not a mathematical signal that the stock has hit a ceiling.

Why Strong Trends Stay 'Overbought'

When a company enters a powerful structural breakout, buying volume swamps supply. Day after day, closes settle higher with only shallow pauses. Because there are few down days to build up the denominator in the formula, RSI quickly charges above 70.

If you short the stock or exit a winning compounder simply because RSI crossed 70, you often sell right at the beginning of the steepest part of the move. In a secular trend, an RSI reading above 70 is confirmation of dominant momentum, not an immediate warning.

The Real Clue: Bearish Divergence

If overbought readings do not signal tops, what does? Divergence. Divergence occurs when the price chart and the momentum gauge disagree with each other.

• Price Action: The stock makes a fresh high (for example, climbing from ₹600 to ₹630, then to ₹650).
• RSI Reaction: Instead of printing a higher reading, RSI registers a lower peak on each subsequent surge (slipping from 76 to 67, then to 58).
• The Interpretation: The car is still rolling forward, but the driver has lifted their foot off the accelerator. The rate of upward progress is slowing.

When you observe a bearish divergence, you do not need to panic. It simply tells you that buyers are expending more effort to achieve smaller price gains. That is the moment to tighten trailing stop losses or pause aggressive fresh purchases.

You can track real-time RSI levels alongside moving averages on any company's technical dashboard on stock-analyze.com to see if an advancing stock still has genuine momentum behind it.