How Time Decay Impacts Your Options Trades

Dhakchanamoorthy S
07 Nov 20247 minutes read
How Time Decay Impacts Your Options Trades

Table of Contents

View All arrow

What is Time Decay?

Example of Time Decay

How to Calculate Time Decay in Options?

How does Time Decay Work?

What is Purchase Annuity, and How Does It Work

How Does Time Decay Affect Options Pricing?

Benefits of Time Decay in Options

Conclusion

In options trading, “time decay” is a critical factor affecting an option’s value. Time decay refers to how an option’s price declines as it gets closer to its expiration date. This factor can significantly impact traders’ profits and losses, making it essential to understand how time decay works. This blog will help you understand time decay, provide examples, explain how to calculate it, and show how it influences options pricing.

What is Time Decay?

Time decay in options occurs when the value of an option decreases as time passes. Every option contract has an expiration date, and as this date approaches, the option loses value because there is less time for the price of the underlying asset to move in a way that benefits the option holder. 

This is called “time decay” or “theta.” It affects both call and put options, reducing their price gradually each day. If the cost of the underlying asset doesn’t change much, time decay can cause the option to become less valuable, making it important for traders to understand and plan for it.

Example of Time Decay

Let’s look at an example to understand time decay better. Suppose you purchase a call option on a stock with a strike price of ₹1000 and pay ₹50 as the premium for the option. 

Now, if the stock price stays around ₹1000 for the next week and doesn’t increase, the premium you paid for the option will start decreasing due to time decay. 

As the expiration date gets closer, the chance of making a profit reduces, so the option’s value drops. After a few days pass, your ₹50 premium could fall to ₹30, even if the stock price hasn’t changed. 

This reduction happens because each passing day leaves less time for the stock to move in your favour. Time decay works against the option holder as the contract nears its expiration.

How to Calculate Time Decay in Options?

Calculating time decay in options is simple if you understand the concept of theta. Theta is a Greek symbol used in options trading to represent time decay. It tells you how much an option’s price decreases each day due to the passing of time. 

To calculate time decay, you can look at the theta value of the option.

For example, suppose an option has a theta of -0.05. In that case, this means the option’s price will drop by ₹5 every day, assuming nothing else changes, like the price of the underlying asset or market volatility. 

Theta is typically provided by most options trading platforms or can be calculated using models like Black-Scholes. You can also use online tools like an option time decay calculator to help you with these calculations.

Time decay usually increases as the option gets closer to its expiration date, meaning the option’s price will drop more rapidly during the last few days of its life. 

So, always check the theta value before buying an option to understand how much you stand to lose due to time decay.

How does Time Decay Work?

Time decay works by gradually reducing the value of an option as the expiration date approaches. Options are priced based on the potential for the underlying asset to move in a favourable direction before the contract expires. 

However, as time passes, the chances of a significant price change become smaller. This is why the value of the option decreases each day, even if the market price of the underlying asset stays the same.

Time decay is not linear. It starts slowly when the option has plenty of time left, but speeds up in the final days before expiration. The closer the option gets to its expiration date, the quicker it loses value. 

This process mostly impacts *out-of-the-money* options, which are less likely to become profitable as time runs out. Understanding how time decay works is key to making smart decisions in options trading.

Wealth Manager

What is Purchase Annuity, and How Does It Work

A purchase annuity is a financial investment product in which an individual makes a lump sum or periodic payment in exchange for receiving regular income payments over a particular period, usually for retirement planning. The purchase annuity meaning can be understood as an investment strategy where the investor secures a steady income stream for a future date, typically after retirement. 

This guaranteed steady income, regardless of market fluctuations or lifespan, makes annuities popular for those seeking long-term financial stability. Whether opting for a fixed or variable annuity, the main idea remains: providing predictable cash flow over time and helping individuals handle their finances during retirement.

How Does Time Decay Affect Options Pricing?

Time decay is crucial in determining an option contract’s fair value or premium. An option’s intrinsic value is the portion of its price that reflects the difference between the underlying asset’s current price and the strike price, only when the option is “in the money.”

The time premium of an option is the portion of its price that exceeds the intrinsic value. This time premium accounts for the potential for future profitability before the option expires and tends to decrease as expiration approaches. This effect is called time decay.

Time decay is most noticeable for at-the-money (ATM) options, where the strike price is close to the underlying asset’s current price. These options have little to no intrinsic value, so their premium is composed primarily of time value, which decays rapidly as expiration nears.

Out-of-the-money (OTM) options, where the strike price is less favorable than the underlying asset’s current price, are also significantly affected by time decay. As expiration approaches, the probability of these options becoming profitable decreases, accelerating the rate of time decay.

Benefits of Time Decay in Options

Here are the benefits of time decay in options:

1. Earn income with selling options

Traders who sell options, like covered calls, benefit from time decay because the option loses value as it nears expiration. The seller gets to keep the premium if the option expires worthless.

2. Reduces risk for sellers

Time decay favours option sellers since the buyer has less chance of profiting as time runs out. This reduces the seller’s risk over time.

3. Faster profits for short-term strategies

For short-term strategies like selling out-of-the-money options, time decay accelerates in the last few days, allowing sellers to profit quickly if the market stays stable.

4. Maximising return with minimal market movement

Time decay allows sellers to make money even if the price of the underlying asset doesn’t move much, as the option naturally loses value.

Conclusion

In conclusion, understanding time decay in options is essential for making informed trading decisions. It is a key factor that influences the price of options as they approach their expiration date. If you’re buying options, time decay can eat your profits, so you must know how quickly the value diminishes. 

On the other hand, if you’re selling options, time decay works in your favour by reducing the value of the contract over time. Knowing how to calculate and manage time decay is crucial no matter which side of the trade you’re on.

Dhakchanamoorthy S

Abhishek Saxena linkedin

A seasoned investment professional with over 17 years of experience in AIF and PMS operations, investments, and research analysis. Abhishek holds an Executive MBA from the Faculty of Management Studies, University of Delhi, and has deep expertise in securities analysis, portfolio management, financial analytics, reporting and derivatives.

Frequently Asked Questions

View All FAQs

Disclaimer: This information is for general information purposes only. Investments in the securities market are subject to market risks, read all the related documents carefully before investing.

rm image

Get your personalized portfolio in 5 mins

The Sunday Investor

Impress your coworkers with your finance insights

sunday investor image

Investing Made Simple

It’s Time to Grow Your Wealth

₹1,000+ cr

AUM

1+ Lac

Investors

stack mb