Math Problem Statement

The correlation between A and B is -0.17. Calculate the maximum possible Sharpe ratio. Express your answer as a decimal rounded to three digits after the decimal point.

Asset Standard Deviation Expected Return F 0 0.03 A 0.50 0.17 B 0.31 0.09

Solution

The maximum Sharpe ratio of a portfolio is calculated using the formula:

Sharpe Ratio=E(Rp)Rfσp\text{Sharpe Ratio} = \frac{E(R_p) - R_f}{\sigma_p}

Where:

  • E(Rp)E(R_p) is the expected return of the portfolio.
  • RfR_f is the risk-free rate.
  • σp\sigma_p is the portfolio's standard deviation.

We are given the following:

  • Risk-free asset FF: Return Rf=0.03R_f = 0.03, Standard Deviation = 0 (as it's risk-free).
  • Asset AA: Expected Return E(RA)=0.17E(R_A) = 0.17, Standard Deviation σA=0.50\sigma_A = 0.50.
  • Asset BB: Expected Return E(RB)=0.09E(R_B) = 0.09, Standard Deviation σB=0.31\sigma_B = 0.31.
  • The correlation between AA and BB is ρA,B=0.17\rho_{A,B} = -0.17.

To calculate the maximum Sharpe ratio, we need to:

  1. Determine the optimal portfolio of AA and BB.
  2. Use the combined portfolio return and standard deviation to compute the Sharpe ratio.

Step 1: Portfolio Expected Return

The expected return of a portfolio is:

E(Rp)=wAE(RA)+wBE(RB)E(R_p) = w_A E(R_A) + w_B E(R_B)

Where wAw_A and wBw_B are the weights of assets AA and BB, respectively.

Step 2: Portfolio Standard Deviation

The standard deviation of a two-asset portfolio is:

σp=wA2σA2+wB2σB2+2wAwBσAσBρA,B\sigma_p = \sqrt{w_A^2 \sigma_A^2 + w_B^2 \sigma_B^2 + 2w_Aw_B \sigma_A \sigma_B \rho_{A,B}}

We will assume the weights wAw_A and wBw_B are optimized to maximize the Sharpe ratio. Let's compute the optimal Sharpe ratio for this portfolio.The maximum possible Sharpe ratio, rounded to three decimal places, is 0.335.

Would you like further details on any part of the calculation, or do you have any other questions?

Here are 5 related questions for further exploration:

  1. How would the Sharpe ratio change if the correlation between AA and BB were 0?
  2. What happens to the portfolio's expected return and risk if you add a third asset?
  3. How can changing the risk-free rate RfR_f impact the optimal portfolio weights?
  4. What is the effect of a negative Sharpe ratio on portfolio performance?
  5. Can the Sharpe ratio alone determine the best investment strategy?

Tip: A higher correlation between assets increases portfolio risk, potentially lowering the Sharpe ratio, unless well diversified.

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Math Problem Analysis

Mathematical Concepts

Portfolio Theory
Risk Management
Statistics

Formulas

Sharpe Ratio = (E(Rp) - Rf) / σp
Portfolio Expected Return = wA * E(RA) + wB * E(RB)
Portfolio Standard Deviation = √(wA² * σA² + wB² * σB² + 2wA * wB * σA * σB * ρAB)

Theorems

Modern Portfolio Theory

Suitable Grade Level

Undergraduate - Finance/Statistics