Solve X-(S+P-C)E^RT+D*E^RT=0 and Isolate C

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To isolate C in the equation X - (S + P - C)E^(RT) + D*E^(RT) = 0, the correct manipulation leads to C = S + P - (X/E^(RT) + D). The discussion highlights the importance of correctly identifying the variables, particularly the different time variables t and T, which affect the calculations. Participants emphasize the need for clarity in the equation's parameters, as well as the significance of the formula in relation to put-call parity in options trading. The conversation also addresses common mistakes, such as sign errors, which can lead to incorrect results. Accurate algebraic manipulation is crucial for determining the correct value of C.
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X-(S+P-C)E^RT+D*E^RT=0

How can I "isolate" C?

Thanks
 
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Assuming E^RT means E^(RT)...

X - (S + P - C)E^(RT) + D*E^(RT) = 0
<=>
X + D*E^(RT) = (S + P - C)E^(RT)
<=>
X/E^(RT) + D = (S + P - C).

Etc.
 
qtiphife,

Please post your questions only once. Triple posting is considered spam.

Thank you,
 
So would this be X/E(RT)+D-S+P= C

Man I am terrible with math.
 
qtiphife said:
So would this be X/E(RT)+D-S+P= C

Close. It should read:

X/E(RT) + D - S + P = -[/color]C

You forgot the negative sign[/color].

Divide both sides by -1, and you're done.
 
Oh yeah, and (rt) have different "T's". Thanks.
 
TIME OUT!

are you saying that in you original realationship that the T is not the same in the 2 expressions where it is used?

X-(S+P-C)E^RT+D*E^RT=0

Do you actually mean

x - (s+ p - C) e^{Rt} + D e^{RT} = 0

If so then

C = x e^{-Rt} + D e^{R(T-t)} - S +P
 
Guys, thanks a ton for your help, however I am still not getting the correct answer. Here are what the letters stand for:

X (Strike Price)= 50
S (Price of underlying) = 51
P (price of put)= 2.125
e (euler's number) = 2.781
R (rate of interest)= .08
t (time until options expire)= 31/365
T (time until dividend paid)= 25/365
D (dividend)=.46
C (price of call) = ?
I keep on getting a negative number. Any help would be much appreciated. Thanks.
 
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It would be more helpful if you were to give the physical signifcance of the equation and parameters. Where did you get it? What is it for? Why can't C be negative?
 
  • #10
Sure,

This formula represents a stock's value with dividend due to the put call parity (kind of a pain to explain), but it has to do with buying or selling a stock (underlying) and buying (selling) and selling (buying) options in order to hedge your position in order to create "edge". X represents the strike price the options are bought, and P is the value of the put and C is the value of the call. I need to know the value of the call.

Please look at my previous post for all of the information.

Thanks!
 
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  • #11
In your previous posts, you only talk of one T. Now there's two : t and T. So, which is which ?

One more thing. Everyone seems to have copied and repeated a line you wrote, with an uncorrected error :

Post #4 : "So would this be X/E(RT)+D-S+P= C"

Besides, the negative C correction, note that the LHS should really be X/E(RT)+D-S-[/color]P. Minus P, not plus.
 
  • #12
Opps! :redface:

You would and should come up with a negitive number, since I lost a negative sign! Try this:

C =S+P- x e^{-Rt} - D e^{R(T-t)}


My apologies for the sloppy algebra!
 
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