Guidelines for Theta/Vega and Theta/Gamma Ratios in overall Portfolio

[sle]

In my view just theta doesn't mean that much... because the risk depends on where you hold the position. You can have a very low theta, but still high risk... if the stock has moved away for instance.

It the theta is low, that means that either the size is not significant or that the moneyness is very low. Either way, it's still a better indicator of risk then any other instantaneous Greek.

I am just saying that if I was able to see/remember a single risk metric for the book (which a trading manager frequently does), I'd make it theta.

 

[destriero]

O... I thought you mentioned something about your friends running big books and looking at that number as their main risk metric...

My bad... I assume they are all just running front month books then? And on one single underlying and not a portfolio of several stocks/indices?

The guy in question worked at Soros (years ago). His risk-manager at the time (Russian-guy) held their vanilla option traders to a 1% figure on their theta. You could go over that figure, marginally, with approval. Small time for you... I am sure you would tell them the error of their ways.

I was stating it is used a book-risk metric.

 

[destriero]

It the theta is low, that means that either the size is not significant or that the moneyness is very low. Either way, it's still a better indicator of risk then any other instantaneous Greek.

I am just saying that if I was able to see/remember a single risk metric for the book (which a trading manager frequently does), I'd make it theta.

^ this guy (sle) ran a derivatives desk at a major bank.

 

[JackRab]

The guy in question worked at Soros (years ago). His risk-manager at the time (Russian-guy) held their vanilla option traders to a 1% figure on their theta. You could go over that figure, marginally, with approval. Small time for you... I am sure you would tell them the error of their ways.

I was stating it is used a book-risk metric.

Make up your mind man... What is it? Risk metric for local gamma or book?

Anyway, good luck with your hear-say stories... cheers.

 

[JackRab]

It the theta is low, that means that either the size is not significant or that the moneyness is very low. Either way, it's still a better indicator of risk then any other instantaneous Greek.

I am just saying that if I was able to see/remember a single risk metric for the book (which a trading manager frequently does), I'd make it theta.

Okay. I'm used to scenario-based risk reviews.

 

[JackRab]

^ this guy (sle) ran a derivatives desk at a major bank.

Awesome... I already knew @sle has some knowledge... but what do you do... drive taxis?

 

[monkeyjoe]

Awesome... I already knew @sle has some knowledge... but what do you do... drive taxis?

Even if he comes off a little harsh, he (@destriero) is really knowledgeable about options and has shared a TON of info (just like @sle) with me and many others over the years.

@monkeyjoe no sorry.. you're right. my bad.

No worries at all. Just trying to be helpful.

 

[sle]

^ this guy (sle) ran a derivatives desk at a major bank.

and I got for it was a lousy T-shirt...

On a serious note, you are both right. On one hand, a lot of experienced people will use theta as the primary proxy to the direction of risk premium in the book. On the other hand, it's impossible to properly manage risk from any single number, either instantaneous or scenario-based. It's especially true in a multi-aset book with a lot of moving parts. So any rule of thumb is simply that, a rule of thumb.

 

[destriero]

Make up your mind man... What is it? Risk metric for local gamma or book?

Anyway, good luck with your hear-say stories... cheers.

Local gamma means, local. Within one sigma, as an example. Pick a time frame. Assumes that the individual is using some sticky model in say, index.

Book refers to your portfolio; global, as in the whole thing.

*IMO* theta is the best single risk-measure in vanilla options. It gives you a dollar-risk, locally, i.e., you were 20K thetas on Monday and you are at 8K thetas on Tuesday. You are either sitting on a gain in vola, or your marks are moving against you. Regardless, it is probably time to cover.

As stated, you really need to stop embarrassing yourself. Hearsay is a word, no hyphen needed. Theta is a greek. I don't believe that theta is of any utility for risk beyond the local-region (Px, underlying, and vol-limits).

 

[destriero]

Awesome... I already knew @sle has some knowledge... but what do you do... drive taxis?

I am the guy that monkey was referring to. I work for a fund in Stockholm. I worked with the other guy that I mentioned, and we both were subject to the Russian risk-manager. I never stated it was the only measure of risk. You stated that I probably used it for premium writing, which would be retarded.