Theta values

cafeole

cafeole

I am fairly new to options, so bear with me. I have looked at several options calculators on the web and I have found quite a discrepancy in theta values. For a particular put option, one calculator showed a theta of -0.5, while the same numbers in another calculator showed a theta of -147. The other greeks were close. What gives?
 
What is an example of the option you are checking? If there is very little time to expiration, like today, some platforms don't properly calculate fractions of a day or ignore them completely. In other words, one thinks there is 100% of one day when another will show 15% of the day left
 
cafeole said:
I was checking the 124 put option on AAPL 4/17/2015 weekly option yesterday.
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Sorry, I calculated that wrong so I deleted what I posted.It would be easier to provide a current value. Time to expiration can make the displayed value different.
 
BTW, I am using 125.5 for stock price, 124.0 for strike, 1 day left to expiration, 2% interest rate, no dividend, vol 14.8
 
rmorse said:
For that put, I see -.08 with the stock here, today.
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upload_2015-4-17_14-57-35.png
 
I think that is probably more in line with the majority. I was just wondering why some online calculators were different. Thanks for the reply.
 
My suggestion is to avoid these online tools for this purpose. If you don't have a live account with a broker that can offer these greeks, open a paper account at one, or a live account and fund it enough to have access. That way you won't have to make adjustments for the inputs.
 
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