Understanding Sharpe Ratio for Risk-Adjusted Returns

Imagine yourself in the role of a financial analyst at a multinational company in Tokyo. You are tasked with comparing different investment portfolios' performances so you can recommend the best one to your company's Chief Investment Officer. In this critical situation, using the Sharpe Ratio as a tool for measuring risk-adjusted return can be incredibly helpful.

What is Sharpe Ratio?

The Sharpe Ratio, developed by Nobel laureate William F. Sharpe, is a measure that helps investors understand the return of an investment compared to its risk. The ratio is the average return earned in excess of the risk-free rate per unit of volatility or total risk. In simple words, it measures the performance of an investment after adjusting for the risk involved.

Why is It Important?

  1. Risk Understanding: It considers both the return and the risk associated with an investment. Many investors mistakenly focus only on returns without considering the risk, potentially leading to unstable results.

  2. Benchmarking: It allows investors to compare the risk-adjusted performance of different portfolios or investments.

  3. Identify the Best Portfolio: By using the Sharpe ratio, investors can identify which investment gives the highest return for a given level of risk.

How is it Calculated?

The Sharpe Ratio is calculated by subtracting the risk-free rate from the portfolio's average return and dividing the result by the standard deviation of the portfolio’s return.

Sharpe Ratio = (Rp - Rf) / σp

Where:

  • Rp = Expected portfolio return
  • Rf = Risk-free rate
  • σp = Standard deviation of the portfolio’s excess return

These components can be easily found or calculated from the available financial data.

Application: Analysing Two Investment Portfolios

Picture two potential portfolios for your company:

  1. Portfolio A has an expected return of 20%, a standard deviation of 18%, and a risk-free rate of 2%.
  2. Portfolio B has an expected return of 15%, a standard deviation of 10%, and a risk-free rate of 2%.

Using the Sharpe ratio, we calculate:

  • Sharpe Ratio(Portfolio A) = (20-2)/18 = 1
  • Sharpe Ratio(Portfolio B) = (15-2)/10 = 1.3

Despite having a higher expected return, Portfolio A's Sharpe ratio is lower than that of Portfolio B, indicating that Portfolio B offers better performance per unit of risk involved. Thus, using this measure as a financial analyst, Portfolio B would be recommended to the Chief Investment Officer.

Conclusion

Understanding the Sharpe ratio not only helps in making informed investment decisions but also in analysing portfolio performance effectively. As an analyst or investor, this knowledge will allow you to take into account both potential returns and inherent risks, leading to more stable and sustainable investment choices.

Test Your Understanding

Imagine you're an investor evaluating two portfolios: Portfolio A offers a return of 7% with a volatility of 3% and Portfolio B offers a return of 8% with a volatility of 5%. Based on the information given, which portfolio seems more attractive?

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