varying maturities. Every security’s yield is based upon investor attitudes and expectations regarding future market
conditions. In other words, the sort of “building” we have done with our yield curves sort of occurs implicitly for
have little guidance regarding the determination of the default risk premium. However, we could assume that the
relationship between corporate bonds of a given rating and Treasury securities of the same maturity would have a
fairly stable relationship. By that token, we might be able to derive a good point estimator of the default risk premium
by looking at the recent average default spread for different rated corporate bonds. This information is as follows:
22.00% 5.00% 3.00% 10.00% 1.02% 11.02% 2.86% 12.86%
32.00% 4.50% 3.00% 9.50% 1.04% 10.54% 2.91% 12.41%
42.00% 4.13% 3.00% 9.13% 1.06% 10.19% 2.97% 12.10%
52.00% 3.80% 3.00% 8.80% 1.08% 9.88% 3.03% 11.83%
mechanism for simulating this relationship. Just as we did for the maturity risk premium, we will “manufacture” a
relationship by which the default risk premium interacts with the time to maturity. The following formula is simply
made up, but it gives us a default relationship with which we are comfortable.
32
33
34
35
36
37
64
65
66
67
68
69
74
75
76
77
78
79
80
81
90
91
92
93
94
98
99
100
101
102
103
104
105
106
107
108
A B C D E F G H I
Years to Real risk-free Inflation Maturity Risk Treasury
Maturity rate (r*) Premium (IP) Premium (MRP) Yield
12.00% 6.00% 2.00% 10.00%
22.00% 5.00% 3.00% 10.00%
30 2.00% 2.30% 3.00% 7.30%
To this point, we have constructed yield curves based upon hypothetical data. The first yield curve operates under
the simple assumption that inflation is expected to rise in the future. To some extent, actual yield curves are
constructed in similar ways. The true Treasury yield curve is determined by graphing Treasury security yields of
Default Risk Premiums and the Liquidity Premium
The construction of corporate yields is a process of beginning with the appropriate Treasury yield curve and adding in
these additional yield premiums. However, the determination of these premiums can be tricky. It seems logical that
default risk on corporate bonds should somehow be a function of the firm’s corporate bond rating. Apart from that we
This tells us the average default spreads of corporate securities with various bond ratings. We will use this data as the
starting point for our corporate yield curves. Naturally, the first question that arises is, “Does the default risk premium
change, or does it always stay the same?”. Logically, the idea of a time-varying default risk premium seems fairly
plausible. The longer the maturity of the security, the greater the possibility of default. Therefore, we need some sort of
DRP t = Default spread * (1.02)(t-1)
With all of that having been said, we can step forward and try to construct corporate yield curves.
Naturally, yield curves can be created for corporate bonds of any rating. However, we have chosen to create curves for
only AAA and B rated bonds. This exercise is for purely illustrative purposes, so rather than complicate the graph
with a lot of curves, we will create two curves to show the relationship between yield curves.
Years to Real risk-free Inflation Maturity Risk Treasury AAA-rating AAA-rated B-rating B-rated
Maturity rate Premium (IP) Premium (MRP) yield DRP bond yield DRP bond yield
12.00% 6.00% 2.00% 10.00% 1.00% 11.00% 2.80% 12.80%
42.00% 4.13% 3.00% 9.13%
52.00% 3.80% 3.00% 8.80%