On page 15 CFAI Vol. 6 2014 is an example referring to the FRA payoff formula.
Short summary of the data given:
FRA expiring in 90d
underlying 180d LIBOR
180d LIBOR at expiration (in 90d) is 6.0%
dealer quotes 5.5%
notional principal 10 million
I understand the formula and so on; however, why we discount the payoff with 1+0.06(180/360) and not with 1+0.06(90/360) since 90 days have been already elapsed? I know that the notes say that this is correct. But, do we discount 90 days “too much” using 180 days?
The FRA in question is essentially an agreement to enter into two 90-day loans starting 90 days from today: a fixed-rate loan and a floating-rate loan. Because the loans would be paid at the end of the loan period, the payoff of the FRA is based on paying 180 days from today; that’s why you discount for 180 days, not for 90 days.
I wrote a couple of articles on FRAs that may be helpful: