Problem bank

Problem 293 of 333MediumLinear AlgebraP293

Hedging one asset with two others

  1. Three assets have standardized daily returns X1,X2,X3X_1, X_2, X_3 (mean 0, variance 1) with correlation matrix

    C=(10.80.50.810.70.50.71)C = \begin{pmatrix} 1 & 0.8 & 0.5 \\ 0.8 & 1 & 0.7 \\ 0.5 & 0.7 & 1 \end{pmatrix}

    You are long asset 3 and want to hedge it with assets 1 and 2, choosing β1,β2\beta_1, \beta_2 to minimize the variance of X3−β1X1−β2X2X_3 - \beta_1X_1 - \beta_2X_2.

    • Find the Cholesky factor LL with C=LLTC = LL^T.
    • Using LL, find the fraction of asset 3's variance that no hedge can remove, and det⁡C\det C.
    • Find β1\beta_1 and β2\beta_2. Does the hedge buy or sell asset 1?