Relative Strength Index (RSI) – Measuring Momentum

After learning about moving averages, Rajesh noticed another panel below the price chart in many trading platforms. It had a single line moving between 0 and 100.

He asked Priya, “What is this extra chart below the price?”

Priya smiled. “That’s RSI - Relative Strength Index. It tells you whether the market is overheated or exhausted.”

What Is RSI?

The Relative Strength Index (RSI) is a momentum indicator that measures the speed and change of price movements.

RSI moves between 0 and 100.

It does not show price levels. It shows momentum strength.

How RSI Is Interpreted?

There are two important levels in RSI:

• Above 70 → Overbought zone
• Below 30 → Oversold zone

These levels help traders understand extreme conditions.

Overbought Condition

When RSI moves above 70:

• Price has risen sharply
• Buying momentum is strong
• The market may be stretched

This does not automatically mean the price will fall. It means upward momentum may slow down.

Rajesh asked, “So should I sell immediately when RSI crosses 70?”

Priya shook her head. “No. Strong trends can remain overbought for a long time.”

Oversold Condition

When RSI moves below 30:

• Price has fallen sharply
• Selling pressure is strong
• The market may be stretched downward

Again, oversold does not guarantee a reversal. It only signals extreme momentum.

RSI in Trending Markets

In strong uptrends:

• RSI often stays between 40 and 80
• Dips near 40 can act as buying opportunities

In strong downtrends:

• RSI often stays between 20 and 60
• Rises near 60 can act as selling opportunities

This shows RSI should always be interpreted in context of trend.

RSI Divergence – Early Warning Signal

Rajesh then noticed something interesting.

“Sometimes price makes a new high, but RSI does not. What does that mean?”

Priya smiled. “That’s called divergence.”

Bullish Divergence

• Price makes lower lows
• RSI makes higher lows

This indicates weakening selling momentum.

Bearish Divergence

• Price makes higher highs
• RSI makes lower highs

This indicates weakening buying momentum.

Divergence often acts as an early warning of potential reversal.

Limitations of RSI

RSI is powerful but has limitations:

• It can remain overbought in strong uptrends
• It can remain oversold in strong downtrends
• False signals occur in sideways markets

Rajesh said, “So RSI should not be used alone.”

Priya nodded. “Exactly. It confirms price behaviour - it doesn’t replace it.”

Combining RSI with Price Action

RSI works best when combined with:

• Support & Resistance
• Trendlines
• Candlestick patterns

For example:

• Hammer near support + RSI oversold = stronger bullish setup
• Shooting Star near resistance + RSI overbought = stronger bearish setup

Rajesh smiled. “So RSI tells me when momentum is stretched.”

Priya replied, “Yes. It helps you avoid chasing extreme moves.”

Rajesh said, “Earlier, I thought RSI was a prediction tool. Now I see it’s a momentum indicator.”

Priya nodded. “Correct. It measures strength, not direction.”

Rajesh smiled. “Trend tells me direction. RSI tells me strength.”

Priya replied, “That’s a complete understanding.”

Key Takeaways

• RSI is a momentum indicator ranging from 0 to 100.
• Above 70 indicates overbought; below 30 indicates oversold.
• RSI behaves differently in trending markets.
• Divergence signals weakening momentum.
• RSI should not be used alone.
• Combine RSI with price action and key levels for better results.