235
Black-Scholes formula where N(x) is cumulative standard no
rmal distribution at x. In other
words, it is the probability that
a variable with a standard normal
distribution, i.e. N(0,1), will be less than x.Note: The equations for the call price and the put price are of course related via the put-call parity, i.e. via
p
t
= c
-St
t
+ PV
(E)t
.
(
)
(
)
() ()T
d
d
T
T
r
S E
d
d
N
S
d
N
Ee
p
d
N
Ee
d
N
S
c
t
t
rT
t
rT
t
t
σ
σ
σ
−
=
⎞ ⎟⎟ ⎠
⎛ ⎜⎜ ⎝
+
+
⎞ ⎟ ⎠
⎛ ⎜ ⎝
=
−
−
−
=
−
=
−
−
1
2
2
ln
1
1
2
2
1
2
Derivative securities: Options - Black-Scholes modelBlack-Scholes model: Pricing formula