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Strategies & Market Trends : How To Write Covered Calls - An Ongoing Real Case Study!

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To: Herm who wrote (6196)12/19/1997 8:49:00 AM
From: Douglas Webb   of 14162
 
My options page is doing fine!
webbindustries.com
I'm getting the 20-minute delayed quotes direct from CBOE now. I've also improved the iterative implied volatility calculations, so short term options won't get that '-' value anymore, and I've added the theoretical put pricing formula from page 479 of McMillian. The volatility for puts and calls come out pretty close on the stocks I've looked at, so I think my approximations on interest and dividends are ok.

I have to say that I wouldn't put too much emphasis on those theta's, especially if there's more than a week or two before expiration. They bounce around a lot, even during the course of a day. I've seen them go to zero, or even slightly positive! That's a side effect of the way I calculate them: I just calculate the theoretical call value for one day less, and report the price difference as the theta. That's not an accurate calculation unless there's a large price difference, and that will only happen near expiration.

Doug.
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