Applying Volatility to Trading

From Volatility to Practical Decisions

So far, we have learned about:

Volatility
Standard deviation
Normal distribution
Expected price ranges

Now we can use these concepts for actual trading decisions.

The source focuses on two practical applications:

Selecting an appropriate Strike Price for writing options
Calculating a volatility-based stop-loss

The purpose is not to predict the market with certainty, but to use probability and historical volatility to make decisions more systematically.

Selecting the Right Strike

One of the biggest challenges for an option writer is selecting the Strike Price.

The trader wants to:

Sell an option
Receive the premium
Reduce the possibility of the underlying moving beyond the chosen strike

There is always a risk that the market will move against the position.

However, volatility and normal distribution can help the trader estimate how far the underlying could potentially move.

This can make Strike selection more structured instead of relying only on guesswork.

Using Standard Deviation to Select a Strike

Suppose the current price of an underlying is ₹10,000.

Historical volatility suggests that the underlying has a certain expected range over the remaining period.

Instead of randomly choosing an OTM Strike, the trader can first calculate a statistical range.

For example:

1 Standard Deviation

Approximately 68% of outcomes are expected to fall within this range under the normal-distribution assumption.

2 Standard Deviations

Approximately 95% of outcomes fall within this wider range.

The trader can then compare these ranges with available Strike Prices.

A Strike that lies further away from the expected range may have a lower probability of being reached, although it can never be considered risk-free.

Why the Distance From Spot Matters

Consider an underlying trading at ₹10,000.

A Call Strike at ₹10,100 is relatively close to the current price.

Another Call Strike at ₹10,500 is much further away.

If the calculated volatility-based range suggests that the underlying is likely to remain below ₹10,500 during the relevant period, the second strike may appear more attractive to an option writer.

However, the further strike will generally offer a different premium.

Therefore, the trader must balance:

Distance from Spot + Probability + Premium Received

This is the basic idea behind using volatility for Strike selection.

Don't Confuse Probability With Certainty

A volatility-based calculation does not guarantee that the underlying will remain within the estimated range.

Markets can experience:

Unexpected news
Sudden volatility
Large price gaps
Extreme movements

The normal distribution framework is therefore a probability tool, not a guarantee.

Events beyond the expected range can occur, including very unusual moves sometimes described as Black Swan events.

Volatility-Based Stop-Loss

Volatility can also be used to determine a more systematic stop-loss.

A fixed stop-loss may not always make sense for every underlying.

For example, a ₹50 movement may be huge for one stock but completely normal for another.

Volatility helps account for this difference.

A more volatile underlying can justify a wider price range, while a less volatile underlying may require a narrower range.

The basic idea is:

Stop-Loss Distance should reflect the underlying's normal price movement.

Why Volatility Matters for Stop-Loss

Suppose two stocks are both trading at ₹1,000.

Stock A

Normally moves only 1% in a day.

Stock B

Normally moves around 4% in a day.

Using exactly the same stop-loss percentage for both may not be appropriate.

A small movement in Stock B may simply be normal volatility rather than a genuine indication that the trade is going wrong.

Therefore, volatility can help traders distinguish between:

Normal Price Fluctuation

and

A Meaningful Adverse Move

Practical Example

Suppose a trader enters a position at ₹1,000.

Historical volatility suggests that a normal daily movement could be around 2%.

A 2% move equals:

₹1,000 × 2% = ₹20

The trader could use this information while determining an appropriate risk level.

The exact stop-loss should depend on the trading strategy, position size and risk tolerance. Volatility simply provides a statistical reference point.

Strike Selection and Stop-Loss Work Together

These two applications are connected.

While selecting a Strike

Volatility helps estimate how far the underlying could potentially move.

While setting a Stop-Loss

Volatility helps estimate what could be considered a normal movement.

Therefore, both decisions can be based on the same underlying concept:

Understanding the expected range of price movement.

A More Systematic Approach

Instead of thinking:

"This strike looks far enough."

A trader can think:

"Based on volatility and the expected range, how far is this strike from the current price?"

Similarly, instead of thinking:

"I'll keep a 2% stop-loss."

The trader can ask:

"Is a 2% movement normal for this underlying?"

This is the shift from instinct-based trading towards model thinking.

Practical Insight

Volatility is most useful when it helps answer a specific trading question.

For example:

How far could the underlying reasonably move?
Which Strike Price is sufficiently away from Spot?
Is the premium attractive relative to the risk?
How much price movement should be tolerated before exiting?

The objective is not to eliminate risk, but to understand and manage it better.

Common Beginner Mistake

A common mistake is selecting an option strike only because it is far away from the current price.

Distance alone is not enough.

The trader should also consider the underlying's volatility, the time remaining and the premium being received.

A strike that looks far away under normal conditions may not be far away during a period of unusually high volatility.

Key Insight

Volatility converts a simple price view into a range-based decision.

It can help traders select option strikes more systematically and create stop-loss levels that account for the normal movement of the underlying.

Key Takeaways

Volatility and standard deviation can be applied to practical trading decisions.
Two important applications are Strike selection and volatility-based stop-losses.
Normal distribution can help estimate the probability of different price ranges.
A trader can compare these estimated ranges with available Strike Prices.
A Strike further from the current price may have a lower probability of being reached, but it is never risk-free.
Premium received must be considered along with the distance of the Strike.
Stop-loss levels should take the underlying's normal volatility into account.
The same fixed stop-loss may not be suitable for assets with different volatility levels.
Volatility helps distinguish normal price fluctuations from potentially meaningful adverse movements.
Volatility is a probability-based tool, not a guarantee of future price movement.