This Exam FM sample reference tests Portfolio Duration under a Common Yield. Bond A is at par, so the common yield is 6%. Its duration is 7.8017 years; the zero prices are 747.26 and 558.39. Weighting all three durations by market value gives 7.4261 years, choice B.
These notes identify the calculation error associated with each wrong letter when that error is reproducible.
AChoice A gives equal one-third weights to the three bond durations rather than market-value weights.
CChoice C omits the five-year zero from the portfolio value and duration numerator.
DChoice D treats both zero-coupon bonds as if they were priced at face.
EChoice E uses face amounts as weights and replaces the coupon bond duration with maturity ten.
Original practice · fully worked
Original variant: zero position required for a target duration
A coupon bond has market value 1,000 and Macaulay duration 7.8 years at a common 6% yield. It is combined with a five-year zero-coupon bond to obtain portfolio duration 6.4 years. Determine the zero's maturity value.
A 1,191.02
B 1,250.00
C 1,300.00
D 1,338.23
E 1,400.00
Variant answer in brief
The duration equation requires the zero to have present value 1000. Accumulating that value five years at 6% gives maturity value 1338.23, choice D.
Setup
Setup
Let Z be the zero's current market value.
1,000+Z1,000(7.8)+5Z=6.4
Model
Model
Solve the market-value weighted duration equation.
7,800+5Z=6,400+6.4Z
Z=1,000
Compute
Compute
Convert the zero's present value to its year-5 maturity amount.
The 2210-page Financial Mathematics Proof Manual reorganizes 461 verified Exam FM solutions by syllabus skill and adds formula proofs, error patterns, and original worked practice.