Thx but they are showing historical or realized volatility, not implied as
far as I can tell.
More to the point is what I'm doing correct or are
there other preferred methods of calculating historical volatility?
-----Original Message-----
From: "dbwyatt_1999" <dbw451@xxxxxxxxxxnet>
Date:
Sat, 14 Nov 2009 14:01:24
To: <amibroker@xxxxxxxxxps.com>
Subject: [amibroker] Re: Trying to plot historical volatility with AFL
I'm not familiar with ivolatility.com, but I would guess
they are calculating an implied volatility based on closing SP option prices
using an option pricing model like Black-Scholes.
Regards,
David
--- In amibroker@xxxxxxxxxps.com,
Potato Soup <potatosoupz@...> wrote:
>
> I'm trying
to plot the 30 day historical volatility of the S&P 500, using the
following AFL on a daily chart with around 2 years of end of day prices for
the S&P 500:
>
> Plot(StDev(Close, 30),"Historical
Volatility", colorOrange,styleLine);
>
> However when
I look at the values, they appear to be a bit off to what I see when I look
online here:
>
> http://www.ivolatility.com/options.j?ticker=SPX:CBOE&R=1&period=12&chart=2&vct=
>
> For today they have 18.99, where as my chart shows 19.348.
All my other values going back further don't match their chart either. Any
ideas, are they calculating it differently than just a simple standard
deviation?
>
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