I am once again asking for your help

Scheweser book 4 fixed income, LOS 32F swap rate curve. I am stuck on how to calculate this and its driving me nuts.

Can someone break down the mathematical sequence to solve the swap fixed rate tenor of 2 years and get their answer 3.98%? The answer is #2 below, but I have no idea how to get solve for it.

Problem starts:

Example: Swap rate curve

Given the following Libor spot rate curve, compute the swap fixed rate for a tenor of 1, 2 and 3 years (i.e., compute the swap rate curve).

Maturity Spot Rate

1 3.00%

2 4.00%

3 5.00%

Answer:

  1. SFR1 can be computed using the equation:

SFR1/(1+S1) + 1/(1+S1) = 1

SFR1/1.03 +1/1.03 = 1; SFR1 = 3.00%

  1. SFR2 can be similarly computed:

SFR2/(1+S1) + SFR2/(1+S2)2 +1/(1+S2)2 =1

SFR2/1.03 + SFR2/(1.04)2+ 1/(1.04)2 =1; SFR2 = 3.98%

Try this:

SFR2/1.03 + SFR2/(1.04)2 + 1/(1.04)2 = 1

(1/1.03)SFR2 + (1/1.042)SFR2 = 1 − 1/(1.04)2 = 1 – 0.9246 = 0.0754

0.9709SFR2 + 0.9246SFR2 = 1 − 1/(1.04)2 = 1 – 0.9246 = 0.0754

(0.9709 + 0.9246)SFR2 = 0.0754

1.8955SFR2 = 0.0754

SFR2 = 0.0754 / 1.8955 = 0.0398 = 3.98%

you need to first calculate the implied forward rate given the spot rates

let its be the spot rate of interest for t years,

it1,t2f be the implied forward rate of interest from years t1 to t2.

it1,t2f = (1+ it2)t2 / (1 + it1)t1 - 1

(a proper financial math book explains in detail how to get to this formula, which is fundamental in finance. if scheweser book doesnt show this, maybe you deserve a refund). it should also be noted that this formula is only applicable for single periods. multi-period implied forward rate is slightly different)

the implied forward rate for year 0 to 1 is just the spot rate, so i1f = i1s = .03

the implied forward rate for year 1 to 2 is:

i2f = (1.042 / 1.031) - 1 = .050097087

the swap rate is calculated as follows:

sum from t = 1 to n of [i<sub>t1,t2</sub><sup>f </sup>x (1 + i <sub>t </sub><sup>s</sup>) <sup>-t</sup>] / [sum from t = 1 to n of ( 1+ its )-t]

thus:

(.03 x 1.03 -1 + .050097087 x 1.04 -2 ) / (1.03 -1 + 1.04 -2 ) = .039802993 = 3.980%

Hey S2000Magician, thanks for this. It worked! Do you know why it doesn’t work when I do it this way? Is it the order or operations? Many thanks.

SFR2/1.03 + SFR2/(1.04)2 + 1/(1.04)2 = 1 SFR2/1.03 + SFR2/(1.04)2 = 0.0754 SFR2/1.03 + SFR2 = 0.0754 * (1.04)2 SFR2/1.03 + SFR2 ​​​​​​​ = .08155 SFR2 + SFR2 ​​​​​​​ = .08155 * 1.03 SFR2 + SFR2 ​​​​​​​ = .084

SFR2 = .042 ​​​​

Hey Thanks for this, but its too complex for me to understand… S2000Magician way worked for me. Thanks Again

Whatever you do to one side of an equation, ya hafta do to the other!!! have a look at where you multiplied the left hand side by 1.042 and later by 1.03. :bulb:

Breadmaker nailed it!

Here, for example, you forgot to multiply SFR2/1.03 by 1.042. If you multiply one term by something, you have to multiply every other term by that same something.

thank you

Hey thanks for this, and for the foresight to know I have no idea what @breadmaker meant when he said I have to do it to the other side of the equation lol. I now feel like I’ve been doing math wrong for my entire life lolol.