CAPM market sensitivity: β_i = dfracCov(R_i, R_m)Var(R_m) — the slope of R_i regressed on R_m, hence the systematic (non-diversifiable) risk loading. To compare firms with different capital structures, unlever observed equity beta: β_U = dfracβ_L1 + (1-t),D/E and relever at the target structure. Rolling beta is non-stationary; Blume and Vasicek shrinkage estimators correct the upward bias in extreme betas toward 1.