Assumption 86
Security returns are not longer correlated for only one reason, i.p.
each security is assumed to respond to the
pull of two or more factors!
t J t F F J t F F J J t J
r
r
A
r
,
, 2
2
,
, 1
1
,
,
...
ε
β
β
+
+
+
+
=
Single-period random cash flows: Factor models - MFM
...
)
,
(
2 2
2
,
2
,
2 1
1
,
1
,
́
+
+
=
⇒
F F K F J F F K F J K J
r
r
Cov
σ β β σ β β (
)
()
0
,
cov
0
2
, 1
cov
= =
K
J
and
F
F
ε
ε