Chapter 13 – Empirical Evidence on Security Returns
13-7
13. When we use the actual factor, we implicitly assume that investors can perfectly
replicate it, that is, they can invest in a portfolio that is perfectly correlated with the
factor. When this is not possible, one cannot expect the CAPM equation (the second
pass regression) to hold. Investors can use a replicating portfolio (a proxy for the
period returns are:
This proxy (PF) has an R-square
with the actual factor of 0.80.
We next perform the first pass
regressions for the two factor
model using PF instead of P: