Volatility
1. Definition
Volatility describes how much and how quickly price changes over time.
A stock that regularly moves 5% in a day is more volatile than one that usually moves 0.5%.
Volatility can expand and contract. It is a market condition, not a permanent personality.
2. Volatility is not direction
A volatile stock can move sharply upward, sharply downward or in both directions.
Volatility measures the size and variability of movement, not whether the movement is bullish or bearish.
3. Daily range
The simplest volatility observation is the high-low range.
A Rs 100 stock with a daily high of Rs 108 and low of Rs 96 had a Rs 12 range, or roughly 12% of the reference price.
Percentage range is more comparable across stocks than rupee range.
4. True range
True range expands the ordinary high-low range by considering gaps from the previous close.
It is the largest of: current high minus current low, current high minus previous close in absolute terms, or current low minus previous close in absolute terms.
This captures overnight movement that the simple intraday range misses.
5. Average True Range (ATR)
ATR is an average of true range over a chosen period.
It expresses typical movement in price units. ATR as a percentage of price makes comparison across stocks easier.
ATR is not a prediction of tomorrow's range. It is a recent historical measure.
6. Standard deviation
Another method measures how widely returns vary around their average.
Standard deviation is widely used in finance, but a beginner does not need the full mathematics immediately.
The practical idea is simple: larger variation means less stable short-term movement.
7. Historical and implied volatility
Historical volatility is calculated from past price movement.
Implied volatility is inferred from option prices and reflects market pricing of future uncertainty.
Because this curriculum focuses first on cash equity, historical movement is the more relevant starting point.
8. Volatility vs risk
Volatility is not automatically loss. A strong uptrend can be volatile and profitable.
Risk includes the probability and size of loss, gap exposure, liquidity, position size, correlation and behavioural errors.
Volatility becomes dangerous when position size and stop distance ignore it.
9. Position sizing and volatility
A volatile stock usually requires a wider structural stop than a stable stock.
If total rupee risk is fixed, a wider stop means fewer shares.
Buying the same number of shares in every stock creates unequal risk.
10. Volatility contraction
When ranges and swings become progressively smaller, volatility is contracting.
Contraction can indicate balance and reduced supply before expansion, but it can also reflect inactivity.
The surrounding trend, volume and liquidity determine the quality of the contraction.
11. Volatility expansion
Expansion occurs when price ranges increase sharply.
It may begin a new trend, confirm a breakout, reflect panic or mark an exhaustion event.
Expansion demands faster risk decisions because price can move farther before orders execute.
12. Regime changes
A stock that behaved calmly for months can become highly volatile after results, regulation, leverage concerns or market stress.
Risk models should update as recent behaviour changes rather than relying on an old fixed assumption.
13. Common beginner mistakes
- Calling all volatility bad
- Movement creates opportunity as well as risk.
- Using the same stop distance for every stock
- Different volatility requires different structural room.
- Using the same share quantity everywhere
- This creates unequal capital risk.
- Treating ATR as a prediction
- ATR describes recent movement; it does not guarantee future range.
- Ignoring volatility expansion after entry
- Changing conditions may require risk reduction or closer monitoring under the trade plan.
14. DStreet principle
Do not fear movement. Measure it, size for it and define what would prove the trade wrong.
15. Beginner checklist
- I know volatility measures the size and variability of movement.
- I separate volatility from direction.
- I understand range, true range and ATR at a basic level.
- I reduce share quantity when stop distance is wider.
- I expect volatility regimes to change.
16. Quick knowledge check
Question: Does high volatility always mean price is falling?
Answer: No.
Question: What does ATR measure?
Answer: Average recent true range.
Question: Why should a volatile stock often have fewer shares?
Answer: To keep total rupee risk controlled with a wider stop.
Question: Is volatility the same as risk?
Answer: No.
17. Next lesson
Gap Up and Gap Down explains overnight price jumps and the execution risk they create.