implied by the price of an option spread trade involving two or more options. Essentially, it is the volatility at which the theoretical value of the spread trade matches the price quoted in the market, or, in other words, the implied volatility
of the spread.
The net volatility for a two-legged spread (with one long leg, and one short) can be estimated, to a first order approximation, by the formula:
where
is the net volatility for the spread
and 
are the implied volatilityand vega
for the long leg
and 
are the implied volatility and vega for the short legIt is now mid-April 2007, and you are considering going long a Sep07/May07 100 call spread, i.e.
...not as much as I am in the metamorphic or sedimentary rock categories. I mean I can take your igneous rocks or leave them. I relate primarily to micas, quartz, feldspar. You can keep your pyroxenes, magnetites and coarse-grained plutonics as far as I'm concerned...
Eunice!? That's a person named Eunice?
I love those old Ventegums.
It so happens, Mr. Simon, that Howard has had discussions with Leonard Bernstein about the possibility of conducting an avalanche ... in E flat.
...you are not Burnsy. Burnsy is Burnsy, I mean Eunice is Burnsy, I mean she isn't Burnsy. Nobody is Burnsy.
It's the television set, Eunice. There's a movie on--a war movie. They're getting dressed for the big battle.
Well, there's not much to see actually, we're inside a Chinese dragon.
Why, those are Howard's. What on Earth are you doing with Howard Bannister's rocks?
Don't kick those rocks, you Philistine!
There is an old Croatian saying, Bollixter, which goes...