RSI and Momentum

9.1 "It's overbought, so it must fall"

Mint read a post saying Bitcoin's RSI was above 70, so it was "overbought" and due for a drop. Mint sold. Bitcoin climbed another 25% over the next three weeks, with RSI staying above 70 almost the whole time.

"The indicator said overbought," said Mint.

"Overbought doesn't mean 'about to fall,'" said Hash. "It means 'has been rising strongly.' In a powerful trend, that's exactly what you'd expect. Let's learn what RSI actually measures, so you don't make that mistake again."

9.2 What momentum is

Momentum is the speed and strength of price movement. A car's position tells you where it is; its speed tells you how fast it's getting somewhere. Momentum indicators measure the market's speed.

Momentum often changes before price does. A car slows down before it stops and turns around. Similarly, a rally often loses momentum before it reverses. That's what makes momentum indicators useful, and also what makes them easy to misread.

9.3 The Relative Strength Index

The Relative Strength Index (RSI) compares the size of recent gains with the size of recent losses, and expresses the result on a scale from 0 to 100. The standard setting uses 14 periods.

RSI = 100 − 100 ÷ (1 + RS), where RS = average gain ÷ average loss

Here's a simplified calculation over 14 days:

	Value
Up days	8, with total gains of $2,800
Down days	6, with total losses of $1,400
Average gain (÷ 14)	$200
Average loss (÷ 14)	$100
RS	$200 ÷ $100 = 2
RSI	100 − 100 ÷ (1 + 2) = 100 − 33.3 = 66.7

Gains were twice as large as losses, so RSI sits in the upper part of the range. The standard RSI uses a smoothed version of these averages, which your charting tool handles automatically, but the idea is the same.

RSI value	Meaning
100	Only gains over the period
Above 70	Strong upward momentum; traditionally called "overbought"
50	Gains and losses roughly equal
Below 30	Strong downward momentum; traditionally called "oversold"
0	Only losses over the period

9.4 Overbought isn't a sell signal

This is the mistake Mint made. In strong trends, RSI can stay above 70, or below 30, for long periods.

In crypto bull markets, Bitcoin's daily RSI has spent weeks in overbought territory while the price kept climbing. In bear markets, RSI has stayed oversold while prices kept falling. Selling just because RSI is above 70 means selling into strength, often too early.

A more useful way to read RSI in trends:

Market condition	How RSI tends to behave	How to use it
Strong uptrend	Mostly stays between 40 and 80+	Pullbacks to 40 to 50 can be buying opportunities
Strong downtrend	Mostly stays between 20 and 60	Rallies to 50 to 60 often fail
Range	Moves between 30 and 70	Overbought and oversold levels work better here

Chapter 9 · RSI zones shift with the trend

Three vertical RSI scales from 0 to 100, with dashed reference lines at 70 (overbought) and 30 (oversold) and a dotted line at 50. In a strong uptrend, RSI mostly stays between 40 and 80 or higher, and the 40 to 50 zone is marked as where pullbacks can be buying opportunities. In a strong downtrend, RSI mostly stays between 20 and 60, and the 50 to 60 zone is marked as where rallies often fail. In a range, RSI moves between 30 and 70, where the overbought and oversold levels work better.

"So RSI zones shift with the trend," said Mint.

"Exactly," said Hash. "In a range, 70 and 30 are useful. In a trend, they're mostly descriptions of what's already happening."

9.5 Divergence

RSI's most valued signal is divergence: when price and RSI disagree.

Bearish divergence: price makes a higher high, but RSI makes a lower high. Price is still rising, but the momentum behind it is weakening.

	Price	RSI
First peak	$104,000	78
Second peak	$108,000	66

Price rose $4,000 higher, but RSI fell. The second push had less force behind it.

Chapter 9 · Bearish divergence

Two stacked panels share a time axis. The top panel shows price rising to a first peak at $104,000, pulling back, then rising to a higher second peak at $108,000, joined by a dashed line labelled higher high. The bottom panel shows the 14-period RSI over the same period: it peaks at 78 under the first price peak and at only 66 under the second, joined by a dashed descending line labelled lower high and momentum fading. Vertical guides connect each price peak to its RSI peak; a dashed reference line marks RSI 70.

Bullish divergence: price makes a lower low, but RSI makes a higher low. Price is still falling, but selling momentum is fading.

Divergences are early warnings, not timing signals. A trend can continue for a long time with divergence, sometimes forming several divergences in a row before it actually turns. Combine them with support and resistance, market structure breaks (Chapter 6), and candlestick confirmation.

9.6 Other uses of RSI

The 50 line. Some traders use RSI above 50 as a sign of bullish momentum and below 50 as bearish, a simple filter for trend direction.

RSI on higher timeframes. Weekly RSI reaching extreme levels has historically coincided with major market phases in crypto, though past patterns don't guarantee future ones.

Failure swings. RSI breaking its own previous high or low can signal a momentum shift before price confirms it.

9.7 Other momentum indicators

RSI isn't the only momentum tool. Two others you'll often see:

Stochastic oscillator. Compares the closing price with the high-low range over a period. It's faster and more sensitive than RSI, giving more signals, and more false ones.

Rate of change (ROC). Measures the percentage change in price over a set number of periods. Simple and direct.

They all measure similar things, so using several together usually adds little. Pick one, learn it well, and understand when it works and when it doesn't.

9.8 Node's critique

"These all seem to be calculated from price," said Node. "So aren't they just price, redrawn?"

"Yes," said Hash. "Indicators don't contain any new information. They're different ways of looking at the same price data. What they do is make certain things easier to see, like whether momentum is fading. That can be helpful, but you're never seeing something price didn't already contain."

That's a healthy perspective for all of the indicators in this module.

9.9 Try it yourself

Add a 14-period RSI to a daily Bitcoin chart. Find a strong uptrend and note how low RSI typically fell during pullbacks. Then find a period of range-bound trading and see how often RSI above 70 or below 30 marked a turning point.

Finally, find one example of bearish divergence and one of bullish divergence, and note how long it took for price to react, if it did.

Key takeaways from this chapter

1. Momentum measures the speed and strength of price moves, and often changes before price turns.
2. RSI compares average gains and losses on a 0 to 100 scale, usually over 14 periods.
3. Overbought and oversold describe strong momentum, not imminent reversals.
4. In trends, RSI zones shift: uptrends tend to hold around 40 to 50, downtrends tend to fail around 50 to 60.
5. Divergence between price and RSI is an early warning, not a timing signal.
6. Stochastic and rate of change measure similar things. Pick one and learn it well.
7. Indicators are derived from price. They help you see, but don't contain new information.