Hi Rembrandt,
Thanks for taking the time to reply.
I understand exactly what you're saying, but I'm still having the same problem. I require quotes on XJO Options which are at least 3 months away from expiry. The normal Black Scholes model doesn't generate anywhere near accurate figures, especially as the time frame increases.
For example, XJO closed yesterday at 4147.8. Going by the ASX web-site, here are a some "fair value" at-the-money quotes based on this (I've also included the IV that I needed to use in the Black Scholes model to generate these figures):
XJOI4 Sep05 4150 Call = 93.3 (IV = 6.6%)
XJOI5 Sep05 4150 Put = 91.5 (IV = 13.5%)
XJOJ3 Dec05 4150 Call = 136.5 (IV = 5.4%)
XJOJ4 Dec05 4150 Put = 123.0 (IV = 14.5%)
XJOKQ Mar06 4150 Call = 166.2 (IV = 1.2%) <-- Impossible!
XJOKP Mar06 4150 Put = 152.5 (IV = 15.7%)
As you can see, the IV's can't be accurate. There is no way a March 2006 Call Option should be priced with an IV of just 1.2%. Furthermore, you can see that the disparity between the IV of the Calls vs Puts increases as the time to expiry increases.
This is why I am assuming that the ex-dividend dates and dividend amounts of the underlying 200 shares making up the XJO are taken into account. This means that Put Options are naturally more expensive than the Call Options, just like when an individual stock has an ex-dividend date occuring within the life of its options.
Are you able to generate the correct prices for longer dated XJO Options, based on your spreadsheet version of the B-S pricing model?
Any further help on this topic would be greatly appreciated...
Jason.