Relationship Between Two Discrete Frequencies
- Suppose rate is compounded times per annum, Let the equivalent rate compounded times per annum be . The rate means that an amount A compounds to:
at the end of one year.
The rate means that an amount A compounds to:
at the end of one year.
Rate compounded times per year is therefore equivalent to rate compounded times per year when:
EXAMPLE –
Suppose the rate is 5% with semi-annual compounding, and the equivalent rate with quarterly compounding needs to be calculated. In this case
The equivalent rate with quarterly compounding is therefore __________________
Spot Rates
- The spot rate is the interest rate earned when cash is received at just one future time. It is also referred to as the zero-coupon interest rate, or just the “zero.”
Suppose USD 100 is invested today and is repaid with USD 120 in three years with no intermediate payments. The three-year spot rate is the rate that equates USD 120 in three years with USD 100 today. If the rate R is measured with annual compounding, then
With semi-annual compounding for example, the rate is given by:
When the discount factor d(t) is applied to this, it should bring it back to 100. Hence:
Par Rates
- The value of the coupon rate for which the value of the bond will be equal to its face value is referred to as the par rate.
- Let A(T) be the value of an instrument that pays USD 1 on every payment date (this is referred to as an annuity):
A(T) = d(0.5) + d(1.0) + d(1.5) + ⋯ + d(T)
It can be easily shown that for a semi-annual paying bond, the par rate is given by
- Suppose the spot interest rates, expressed with semi-annual compounding, for 0.5, 1.0, 1.5, and 2.0 years be 4%, 5%, 5.5%, and 6% (respectively).
The two-year par rate (%) is
Thus, a two-year bond paying a coupon semi-annually at a rate of __________________ per year is worth par.
Valuing Bond Using Par Rates
- The par rate in conjunction with the annuity factors A(T) to provide a way of valuing bonds with other coupons. Consider a bond with maturity T, coupon c, and a face value of 100. The value of the bond (V) is
It is known that:
Substituting for d(T)
In the earlier example, the par rate is _________________. When the coupon is ___________, this formula gives the value of the bond as:
Forward Rates
- Forward rates are the future spot rates implied by today’s spot rates. For example, suppose the offered one-year rate is 3% and the offered two-year rate is 4% (both with annual compounding). Suppose F is the forward rate for the second year. The forward rate is such that USD 100, if invested at 3% for the first year and at a rate of F for the second year, gives the same outcome as 4% for two years. This means that:
- When rates are expressed with semi-annual compounding (as is frequently the case in fixed-income markets), an extension of this analysis shows that the forward rate per six months for a six-month period starting at time T is
- where
are the spot rates for maturities T and T + 0.5 (respectively) with semi-annual compounding. Thus, the annualized forward rate expressed with semi-annual compounding is twice this.
- When rates are expressed with continuous compounding, the forward rate for the period between time is
where
is the spot rate for maturity is the spot rate for maturity . This formula is approximately true when other compounding frequencies are used for the rates.
- When forward rates for successive periods are compounded, spot rates are obtained. For example, suppose all rates are expressed with semi-annual compounding, and that
are forward rates in n successive six-month periods. Then:
Thus, if a large financial institution can borrow or lend at spot rates, it can lock in the forward rate.
Properties Of Spot, Forward, And Par Rates
- Key properties of the rates discussed till now are as follows:
- If the term structure is flat (with all spot rates the same), all par rates and all forward rates equal the spot rate.
- If the term structure is upward-sloping, the par rate for a certain maturity is below the spot rate for that maturity.
- If the term structure is downward-sloping, the par rate for a certain maturity is above the spot rate for that maturity.
- If the term structure is upward-sloping, forward rates for a period starting at time T are greater than the spot rate for maturity T.
- If the term structure is downward-sloping, forward rates for a period starting at time T are less than the spot rate for maturity T.
- The situation for an upward-sloping term structure case is illustrated in this Table.
Maturity (yrs) |
Spot |
6-Month Fwd |
Par |
0.5 |
2.01 |
4.04 |
2.01 |
1 |
3.02 |
4.86 |
3.01 |
1.5 |
3.63 |
5.27 |
3.62 |
2 |
4.04 |
5.83 |
4.01 |
2.5 |
4.40 |
5.94 |
4.36 |
3 |
4.65 |
6.24 |
4.60 |
3.5 |
4.88 |
6.36 |
4.82 |
4 |
5.06 |
6.54 |
4.99 |
4.5 |
5.23 |
6.67 |
5.14 |
5 |
5.37 |
|
5.28 |
- The situation for a downward-sloping term structure case is illustrated in this Table.
Maturity (yrs) |
Spot |
6-Month Fwd |
Par |
0.5 |
5.06 |
4.24 |
5.06 |
1 |
4.65 |
3.73 |
4.66 |
1.5 |
4.35 |
3.73 |
4.36 |
2 |
4.19 |
3.17 |
4.21 |
2.5 |
3.99 |
3.07 |
4.01 |
3 |
3.84 |
3.12 |
3.86 |
3.5 |
3.73 |
3.08 |
3.76 |
4 |
3.65 |
3.10 |
3.68 |
4.5 |
3.59 |
3.08 |
3.62 |
5 |
3.54 |
|
3.57 |
Flattening And Steepening Term Structures
- A flattening term structure occurs
- When long- and short-maturity rates both move down, but long-maturity rates move down by more than short-maturity rates (known as a bull flattener); or
- When long- and short-maturity rates both move up, but short-maturity rates move up by more than long-maturity rates (known as a bear flattener).
- A steepening term structure occurs
- When long- and short-maturity rates both move down but short-maturity rates move down by more than long-maturity rates; or
- When long- and short-maturity rates both move up, but short-maturity rates move up by less than long-maturity rates.
- Note that a flattening term structure is not necessarily one that becomes flatter and a steepening term structure is not necessarily one that becomes steeper. If a term structure is already upward-sloping, then a steepening will cause it to be more upward-sloping and a flattening will cause it to be less upward-sloping. But if it is downward-sloping, the reverse is true. The steepening/flattening language refers to the relative rate movements and does not depend on the initial slope of the yield curve.
- Suppose a trader thinks the current upward-sloping term structure will steepen so that 20-year rates increase faster than ten-year rates. The trader can short 20-year bonds and buy ten-year bonds. If the trader is right, the 20-year bonds will decline in value relative to the ten-year bonds and the trader will make money. Similarly, a trader who thinks that the term structure will flatten should buy 20-year bonds and short ten-year bonds.