Consider an equally-weighted portfolio comprised of five assets in which the average asset standard deviation equals 0.57 and the average correlation between all asset pairs is ?0.21. The variance of the portfolio is closest to:
Portfolio variance = σ2p = (1 / n) σ 21 + [(n - 1) / n]cov
ρ1,2 = (cov1,2) / (σ1 σ2) therefore cov1,2 = (ρ1,2)(σ1 σ2) = (?0.21)(0.57)(0.57) = ?0.068
σ2 = (0.57)2 = 0.32
σ2p = (1 / 5)(0.32) + (4 / 5)(?0.068) = 0.064 + (?0.0544) = 0.0096 or 1.00%
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