# Jensens Alpha - definition & overview

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Jensens Alpha is a portfolio performance metric measuring excess return over a benchmark. A positive alpha indicates outperformance vs the benchmark.

Jensens Alpha, also known as the Alpha coefficient, is a key term in the world of small business finance. It's a measure used to determine the performance of an investment or a portfolio, compared to its expected return given its level of risk. In essence, it's a way of quantifying how much value an investment manager adds (or subtracts) from a portfolio. It's named after its creator, Michael Jensen, an American economist renowned for his work in financial economics.

For small businesses, understanding Jensens Alpha can be instrumental in making informed investment decisions. It can help identify investments that are outperforming or underperforming, and guide strategic decisions about where to allocate resources. It's a tool that can help small businesses maximise their returns and minimise their risks, contributing to their overall financial health and sustainability.

## Understanding Jensens Alpha

Jensens Alpha is calculated by comparing the actual return of an investment to its expected return, given its level of risk. The expected return is determined using the Capital Asset Pricing Model (CAPM), which takes into account the risk-free rate of return and the investment's beta (its sensitivity to market movements).

If the actual return is higher than the expected return, the Jensens Alpha is positive, indicating that the investment has outperformed the market. If the actual return is lower than the expected return, the Jensens Alpha is negative, indicating that the investment has underperformed the market. A Jensens Alpha of zero indicates that the investment has performed exactly as expected, given its level of risk.

### Calculating Jensens Alpha

The formula for calculating Jensens Alpha is: Alpha = Actual Return - Expected Return. The expected return is calculated using the CAPM, which is: Expected Return = Risk-Free Rate + Beta * (Market Return - Risk-Free Rate).

By substituting the CAPM into the Alpha formula, we get: Alpha = Actual Return - [Risk-Free Rate + Beta * (Market Return - Risk-Free Rate)]. This formula allows us to calculate the Jensens Alpha for any given investment, given its actual return, risk-free rate, beta, and market return.

### Interpreting Jensens Alpha

A positive Jensens Alpha indicates that an investment has outperformed the market, given its level of risk. This could be due to a variety of factors, such as superior management, favourable market conditions, or simply good luck. It's important to note, however, that a positive Jensens Alpha does not necessarily mean that an investment is a good choice. It simply means that it has performed better than expected, given its level of risk.

A negative Jensens Alpha, on the other hand, indicates that an investment has underperformed the market, given its level of risk. This could be due to poor management, unfavourable market conditions, or bad luck. Again, a negative Jensens Alpha does not necessarily mean that an investment is a bad choice. It simply means that it has performed worse than expected, given its level of risk.

## Applications of Jensens Alpha

Jensens Alpha can be used in a variety of ways to inform investment decisions. For example, it can be used to evaluate the performance of a portfolio manager, by comparing the actual return of the portfolio to its expected return, given its level of risk. If the portfolio's Jensens Alpha is positive, it indicates that the manager has added value to the portfolio. If it's negative, it indicates that the manager has subtracted value.

Jensens Alpha can also be used to compare the performance of different investments or portfolios. By calculating the Jensens Alpha for each investment, you can identify which ones are outperforming or underperforming the market, given their level of risk. This can help guide decisions about where to allocate resources, to maximise returns and minimise risks.

### Limitations of Jensens Alpha

While Jensens Alpha is a useful tool for evaluating investment performance, it's important to be aware of its limitations. First, it assumes that the relationship between risk and return is linear, which may not always be the case. Second, it assumes that the risk-free rate and the market return are constant, which is rarely the case in the real world.

Furthermore, Jensens Alpha is a historical measure, meaning it's based on past performance. While past performance can be a useful guide, it's not a guarantee of future performance. Therefore, while a positive Jensens Alpha may indicate that an investment has performed well in the past, it doesn't necessarily mean it will perform well in the future.

## Conclusion

In conclusion, Jensens Alpha is a powerful tool for evaluating investment performance. It can help small businesses make informed decisions about where to allocate resources, to maximise returns and minimise risks. However, like all tools, it's not infallible. It's important to use it in conjunction with other measures and to be aware of its limitations.

By understanding and applying Jensens Alpha, small businesses can gain a competitive edge in the market, enhance their financial health, and pave the way for sustainable growth and success. It's a testament to the power of informed decision-making and strategic resource allocation in the world of small business finance.