Skip to content
All library documents

Valuing a Floating-Rate Note with a Par Swap Curve

Article Quant Q&A · Author: Alex F

Summary

The discussion explains how to value a five-year arrangement in which an investor pays par, receives LIBOR plus a spread annually, and gets principal back at maturity. It treats the cash flows as a floating-rate note (FRN): a LIBOR-only FRN valued at par plus an annuity representing the spread payments. The par value of the LIBOR component offsets the initial payment, leaving the spread annuity as the deal’s net value.

For discounting, the response says to bootstrap discount factors from the par swap curve and apply them to the spread payments. It cautions against using the bond’s yield to maturity, since that yield reflects the separate bond and is not the appropriate curve for valuing these swap-related cash flows. The post outlines the valuation logic but does not provide the bootstrapping steps, computed discount factors, or a numerical value for the spread annuity.

Key ideas

  • A LIBOR-plus-spread floating-rate note can be decomposed into a par LIBOR note and an annuity of spread payments.
  • The par LIBOR note offsets an initial payment of par, leaving the spread annuity to determine the deal’s value.
  • Discount the spread payments using factors bootstrapped from the par swap curve.
  • The bond’s yield to maturity is not the discount rate for valuing the floating-rate arrangement.

Tags

Full text
# Valuing an interest rate swap using a par swaps curve?


# Valuing an interest rate swap using a par swaps curve?












I've worked through this problem already and was hoping for some feedback on my approach. The problem description is:

You have a notional amount of 100 million paying fixed coupons of 8% annually for 5 years. You bough the bonds at a discount for 92.418, implying a YTM of 10%. You want to enter an agreement to repackage these bonds. The agreement you will enter is to provide $100 for each bond purchased and will receive receive LIBOR plus a 40 basis point spread as the floating rate for 5 years. You will also receive a repayment of the 100 principal at maturity. These floating rate payments will take place at the end of each year (i.e. annually) to match the payments on the bond and up to and including the final maturity in year 5.

The par swaps curve is given as:

```
Maturity                        1 Yr    2 yr    3 yr    4 yr    5 yr
Par swaps rate against LIBOR    9.50%   9.59%   9.62%   9.69%   9.70%
```

Now I'm slightly confused by the wording in the question. it says `{you} will provide $100 for each bond purchased` meaning I pay an initial cash outflow of 100, while I will receive `LIBOR plus 40 basis point(s)`. So it doesn't seem to be a true interest rate swap, but more of an intitial payment by me to receive floating coupons over the 5 years.

I've structured my cash flow calculation accordingly.

```
Years               0       1       2       3       4       5
Par Swap Rate               9.50%   9.59%   9.62%   9.69%   9.70%
Pmt -100                    9.5     9.59    9.62    9.69    109.7
PV(Pmt)             -100    8.636   7.926   7.228   6.618   68.115
PV(bond)                                                    -1.477
```

The `PV(Pmt)` is calculated as $\frac{1}{(1+YTM)^{i}}$ and the `Pv(bond)` is the sum of the `Pv(Pmt)`. The part I'm most unsure on is my discount factor being the 10%. I don't believe this is correct. Could someone confirm or deny if this is correct, and if I'm wrong provide some feedback on the correct approach?

## Answer by ZRH (score 1)

https://quant.stackexchange.com/a/44193

My understanding is as follows - you pay 100 at $T=0$, receive LIBOR+40bp annually, and get back 100 at the end of the deal. This is actually a cash outflow of 100, plus a floating rate note (FRN). The FRN with a 40bp spread (i.e. the one that pays LIBOR + 40bp) can be decomposed into a LIBOR flat FRN (priced at 100), plus a 40bp annuity paid out at $T=1,2,...,5$. The initial outflow of 100 and the NPV of the par FRN net out, so the value of the deal is that of the 40bp annuity.

To value this, DO NOT use the YTM value derived for the bond, but bootstrap the par swap curve, and derive the discount factors for $T=1,2,...,5$ and apply them to the 40bp annuity.

Shown in full with attribution under the source's licence. Licence: CC BY-SA 4.0 (Stack Exchange)

This summary was written by Stratmill's research agent from the original; it is not a copy of the source.