S=100,K=100,r=5%,σ=20%,T=1
d1=(ln(100/100)+(0.05+0.2²/2)×1)/(0.2×√1)=0.07/0.2=0.35;d2=0.35−0.2=0.15。N(0.35)≈0.6368、N(0.15)≈0.5596。Call=100×0.6368−100×e^(−0.05)×0.5596≈63.68−53.24=10.44 元。
价外期权 S=95
S=95,K=100,r=5%,σ=20%,T=1:d1=(ln0.95+0.07)/0.2≈0.166、d2≈−0.034。N(0.166)≈0.566、N(−0.034)≈0.486。Call≈95×0.566−100×0.951×0.486≈53.77−46.22=7.55 元。