Because of the possibility of disinflation (i.e., price declines), the inflation-adjusted principal at
maturity may turn out to be less than the initial par value. However, the Treasury has structured
TIPS so that they are redeemed at the greater of the inflation adjusted principal and the initial par
value.
An inflation-adjusted principal must be calculated for a settlement date. The inflation-adjusted
principal is defined in terms of an index ratio, which is the ratio of the reference CPI for the
settlement date to the reference CPI for the issue date. The reference CPI is calculated with
a three-month lag. For example, the reference CPI for May 1 is the CPI-U reported in February.
The U.S. Department of the Treasury publishes and makes available on its website
(www.publicdebt.treas.gov) a daily index ratio for an issue.
(c) Suppose that the coupon rate for a TIPS is 3%. Suppose further that an investor
purchases $10,000 of par value (initial principal) of this issue today and that the semiannual
inflation rate is 1%.
Answer the below questions.
(1) What is the dollar coupon interest that will be paid in cash at the end of the first six
months?
In our example, the coupon rate for a TIPS is 3%, the annual inflation rate is 2%, and an investor
purchases today $10,000 par value (principal) of this issue. The semiannual inflation rate is 1%
(2) What is the inflation-adjusted principal at the end of six months?
As seen in part (1) when computing the coupon payment, we find that the inflation adjusted
(d) Suppose that an investor buys a five-year TIP and there is deflation for the entire
period. What is the principal that will be paid by the Department of the Treasury at the
maturity date?
With deflation, the inflation-adjusted principal would fall. However, the Treasury has structured
TIPS so that they are redeemed at the greater of the inflation adjusted principal and the initial par