Beta measures how a stock or a portfolio moves vis-à-vis the market. In other words, beta compares the volatility in a stock with that of the market. For the market, we take a benchmark index like Sensex or Nifty.
The market is supposed to have a beta of 1. If a stock has a beta of more than 1, it means that it moves more than the market. However, if a stock has a beta of less than 1, it means that it moves less than the market. If a stock has 1 as its beta, it shows that it moves exactly by as much as the market moves.
Beta is used by analysts and market participants while using the Capital Asset Pricing Model (CAPM) to calculate the estimated returns from a security. Now that we have explained what beta is, let us delve deeper into this topic.
What is Beta in Stocks?
Let us understand the meaning of beta with a few examples. Suppose a stock’s beta is 1.2, it means that it is 20% more volatile than the market. If the market is up by 10%, this stock will be up by 12% [10*(1+20%)]. Conversely, if the market is down by 10%, this stock will be down by 12%.
Most importantly, beta is the measure of systematic risk or market risk. This risk cannot be eliminated by portfolio diversification.
However, you can decide to take more risk than the market, less risk than the market, or the same risk as the market. If a stock’s beta is less than 1, it is less risky than the market. Suppose a stock’s beta is 0.8, it means it is 20% less volatile than the market. If the market moves up by 10%, it will move up by 8%. If the market moves down by 10%, it will fall by 8%.
The formula for beta is as follows:
Beta = Covariance between a stock’s or portfolio’s return with the market’s return / Variance of the market's returns
BETA in Theory vs. BETA in Practice
If you are an investor, you must understand how beta performs in real-market scenarios vis-à-vis theory. In theory, we assume that stock returns are normally distributed. However, when you start trading in the market, you will notice that stock returns are not always normally distributed.
Imagine that a stock has an extremely low beta. It means that it will have smaller price swings compared to the market. But, this stock's price can be declining over a long period of time. Now, if you add this stock to your portfolio, you could incur losses because its price is falling. However, since it has a low beta, it has a lower volatility than the market.
On similar lines, consider a stock with a high beta and a price mostly moving upwards. It can increase your portfolio's risk because it has a high beta. But, it can also help you make a profit because its price is mostly moving upwards.
Additional Read: What is a Stock Symbol?
Types of BETA in the Stock Market
There can be several types of beta in the stock market, as explained below:
Negative Beta:
If a stock has a negative beta, it means that it has an inverse relationship with respect to the market. When the market moves up, it will fall. When the market falls, it will move up.
Zero Beta:
If a stock has zero beta, there is no correlation between its price and the market. Whether the market goes up or down, this stock’s price is not expected to change based on the market.
0<Beta<1:
If a stock has less than one but more than 0 beta, it means that it moves in the direction of the market; however, it moves lesser than the market. For example, if a stock has 0.7 beta, it will move up by 7% when the market moves up by 10%. When the market moves down by 10%, it will move down by 7%.
Beta = 1:
If a stock’s beta is 1, then it will move up and down by exactly how much the market is moving up and down.
Beta>1:
If a stock’s beta is more than one, it will move in the direction of the market. However, it will move more than the market. For example, if a stock has 1.4 beta, then when the market moves up by 10%, it will move up by 14%. When the market moves down by 10%, it will fall by 14%.
How to Calculate Beta?
Understanding what is beta is important for anyone analysing stock performance. In the stock market, beta is a measure of how much a stock’s price moves compared to the market as a whole. It shows whether a stock is more or less volatile than the broader market.
Beta is calculated by comparing a stock’s past returns with those of the overall market using a statistical method called regression analysis. The slope of the line in this analysis is the beta coefficient, which tells us how sensitive the stock is to market movements.
Here’s how to calculate beta:
Beta (β) = Covariance (Re, Rm) / Variance (Rm)
Where:
- Re is the return of the individual stock
- Rm is the return of the market
- Covariance shows how the stock’s returns move with the market
- Variance indicates how much the market’s returns vary
A beta of 1 means the stock typically moves in line with the market. A beta above 1 means the stock is more volatile (high-beta), and a beta below 1 means it’s less volatile (low-beta). Understanding what is beta in stocks helps investors align their stock choices with their tolerance for market risk.
The Role of Beta in Investment Decisions
Beta helps you assess the risk inherent in a stock. Once you have assessed the beta of several stocks, you can diversify your portfolio. For example, you can create a portfolio comprising a few stocks with a beta higher than 1 and a few stocks with a beta less than 1.
Beta also helps you estimate the expected return from a security by using the CAPM model. As per this model, the expected return from a security can be measured by using this equation:
Expected return from a security = Risk-Free Rate + β×(Market Return−Risk-Free Rate)
Comparing Beta with Other Risk Metrics
Let us compare beta with other popular risk metrics in the stock market. As we already said, beta compares the volatility of a stock with that of the market. It shows the risk inherent in a stock due to the market. Hence, beta is a measure of market risk or systematic risk.
On the other hand, standard deviation measures the spread of an asset’s returns over its average returns. Standard deviation does not compare the return of a stock with that of the market. But, it is a good measure for comparing the volatility of stock with that of other stocks.
Then, we also have Sharpe Ratio, which measures the return earned for every unit of risk undertaken by owning a stock. This is calculated by dividing the difference between the return on a stock and risk-free rate with the standard deviation of that stock. Sharpe Ratio combines the risk and return of a stock in one number, which is its strength. However, like beta, it assumes that a stock’s returns are normally distributed, which may not be the case always.
Advantages of Using Beta in the Stock Market
Helps Assess Market Volatility
Beta allows investors to evaluate how sensitive a stock is to market movements. High-beta stocks move more than the market, while low-beta stocks move less. This helps investors choose stocks that match their risk comfort.
Supports Risk-Based Portfolio Planning
By combining high-beta and low-beta stocks, investors can build portfolios suited to their investment goals. Conservative investors might prefer low-beta stocks, while those willing to accept more fluctuation may include high-beta stocks.
Reflects Past Stock Behaviour
Beta shows how a stock has performed in comparison to a benchmark index in the past. This historical data can offer insights into how a stock may behave in similar market conditions.
Assists in Comparing Stocks
Beta helps compare different stocks in terms of how they respond to market changes. This makes it easier for investors to identify which stocks fit within a desired risk profile.
Guides Dividend and Growth Strategies
Investors focused on dividend income may lean toward low-beta stocks, which tend to be more stable. On the other hand, growth-focused investors might consider high-beta stocks, which often react strongly to market trends.
Limitations of Using Beta in the Stock Market
Based on Past Data Only
Beta is calculated from historical stock and market returns. It does not predict future performance, especially during times of economic or political uncertainty.
Ignores Company-Specific Issues
While beta reflects market-related risk, it does not include company-specific problems like poor leadership, legal cases, or high debt levels. These internal factors can still affect stock prices significantly.
Less Reliable During Market Shocks
High-volatility periods may cause stocks to move unpredictably. During such times, beta may not provide an accurate measure of a stock’s real-time risk.
Not a Complete Risk Measure
Beta does not account for unsystematic risks — risks specific to individual companies. Investors need to look at other factors in addition to beta when analysing a stock.
May Mislead if Used Alone
Using beta alone to make decisions can be risky. It’s just one tool among many that investors should consider when assessing a stock’s suitability in their portfolio.
Conclusion
Over many decades, beta has emerged as a powerful measure for stock trading, portfolio management, and option trading. By comparing a stock’s volatility with the market, it provides compelling insights to investors. However, it has limitations as well. For example, it assumes that an asset’s returns are normally distributed, which may not be the case always. Therefore, investors should be aware of the strengths and limitations of beta while using it.
Disclaimer: Investments in the securities market are subject to market risk, read all related documents carefully before investing.
This content is for educational purposes only. Securities quoted are exemplary and not recommendatory.
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