Quote from ctarmor-et:
It could be the way the diff vendors calculate it ... for example in balck-schooles one may use the interest rate from the otr tsy 10yr, other may use the 30yr ...
Quote from jnbadger:
Also I noticed you're using the Prophet Chart for your IV.
I tried FCX on the TOS Charts and it gave a different picture for the IV. You'll have to add an avg, but at least it doesn't have the weird sudden drop off in IV.
Hope this helps.