delta depreciation

Quote from tradingjournals:

Test it. Give me some hypothetical ATM deltas (no carry), stock price, keep the rest with you, and see if I can get the price of the option.

stock = 47

delta = .5173
 
Quote from tradingjournals:

~1.62 (if I did not make miscalculations)

If I am right give people data to test for themselves.

credit where credit is due.

You are correct. Pretty cool trick. I see how you do that. Thanks.
 
Quote from atticus:

Sure, you can solve for price in premium and vol given a precise delta figure (and solve for other greeks/moments), but the fact remains that the impact to delta from vol is lower than rho under most circumstances.
 
Quote from donnap:

credit where credit is due.

You are correct. Pretty cool trick. I see how you do that. Thanks.

Thanks for your comments and for keeping the tricks personal. I have been wondering if I should publish such little things (which I have not seen anywhere else) in a book I have been thinking to publish-- On one hand they may provide uniqueness and possibly some demonstrated "expertise" to the book, , but on the other hand readers may not want to see too many people looking from the same angles as themselves. :p

Cheers!
 
Quote from saminny:

Can you share the trick?

Donnap was the first to give the data, and to learn from the solution, so she deserves to know it, as she has earned it.

I think Donnap is doing the right thing to keep it from public, unless the trick is well known elsewhere, which I have not seen. If no one before me has come up with it, I believe I have intellectual rights on it.
 
Okay I think I got it :D

You derived it like that:

2*spot*(delta-0.5)

ATM, N(d1) and N(d2) are symmetrical around 0.5. That means, N(d1)-N(d2)=2*(N(d1)-0.5)=2*(delta-0.5)
Because there is 0 cost of cary, ATM S=K
And a call is

C=SN(d1)-K(Nd2)
C=SN(d1)-SN(d2)
C=S*2*(N(d1)-N(d2))=S*2*(delta-0.5)

Am I missing something ?
 
Quote from tradingjournals:

Test it. Give me some hypothetical ATM deltas (no carry), stock price, keep the rest with you, and see if I can get the price of the option.
stk = 50
delta = .55
 
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