CAPM Flashcards
Return of an asset (probabilities)
r_a = p1r1 + p2r2 + p3*r3
Variance of an asset (probabilities)
Var_a = p1(r_a1 - r_a)^2 + p2(r_a2 - r_a)^2 + p3*(r_a3 - r_a)^2
Covariance (probabilities)
cov = p1(r_a1 - ra)(r_b1 - r_b) + p2(r_a2 - ra)(r_b2 - r_b) + …
Return of a portfolio
r_p = xa * ra + xb * rb
Variance of portfolio (basic)
Var_p = xa^2 * Var_a^2 + xb^2 * Var_b^2 + 2xaxb*cov_ab
Variance of portfolio (3 assets)
Var_p = xa^2 * Var_a^2 + xb^2 * Var_b^2 + xc^2 * Var_c^2 + 2xaxbcov_ab + 2xaxccov_ac + 2xbxc*cov_bc
Variance of portfolio (Cov_ap)
Var_p = xacov_ap + xbcov_bp
Variance of portfolio (with beta)
Var_p = (beta*sd_m)^2 + Var(e)^2
Covariance ab
Cov_ab = Cor_ab * sd_a * sd_b
Covariance ap
Cov_ap = xavar_a + xbcov_ab
Covariance ap (3 assets)
Cov_ap = xavar_a + xbcov_ab + xc*cov_ac
Correlation ab
Cor_ab = Cov_ab/(sd_a * sd_b)
Beta_a (Var_m)
Beta_a = Cov_am/Var_m
Beta equality
1 = xabeta_a + xbbeta_b
Beta_a (premiums)
Beta_a = (ra-rf)/(rm-rf)
Beta_p
Beta_p = xa * beta_a + xb * beta_b
R^2
Sqrt(R2) = Cor_am = (Beta_a * Sd_M) / Sd_A
Total, systematic, non-systematic variance
Var_a = Beta_a^2 * Var_m + Var(e_a)
Proportion of total risk that can be diversified away
Sd(e_a)/Sd_a = 1 - (Beta_a*Sd_m)/Sd_a = (Sm - Sa) / Sm
MVP
Xa (MVP) = (Var_b - Cov_ab) / (Var_a + Var_b - 2*Cov_ab)
Risk contribution
Risk cont = Beta_a * Xa
Holding Period Return
HPR = (P1 - P0 + d)/P0 = P1/P0 - 1
Total return
R = 1 + r