TRADING CASE B04
Duration hedging and bond immunization
LEARNING OBJECTIVE
Understand duration and apply the bond immunization theorem to hedge a liability against parallel yield-curve shifts.
KEY CONCEPTS
Duration  |  Interest-rate risk  |  Bond immunization theorem  |  Parallel yield-curve shifts

HOW THE CASE WORKS

Four fixed-income securities have cash flows extending up to four years. Trading occurs only on Day 1 of Year 1. You begin with a liability in non-tradable Security 1 or 2 and may trade only the 2-year and 3-year zero-coupon bonds.

Prices are set through bids and asks. Borrowing and short selling are allowed. Short positions must make any cash payment due. Year 1 interest is applied to the closing money-market balance before security payments.

REALIZED YIELD CURVE

The Year 1 spot rate is 25%. The initial yield curve is flat at 25%. At the end of Year 1 it remains flat, but can shift by as much as +/-20 percentage points.

After the shift, all remaining cash flows are marked using the new flat curve. A shift to 15% values the 3-year zero at 100/(1.15^2) and the 2-year zero at 100/1.15.

INITIAL POSITIONS - TWO TRADER TYPES

PositionType IType II
Security 10-14
Security 2-290
2-year zero051
3-year zero840
Cash3,2005,000

SECURITY CASH FLOWS

SecurityPeriod 1Period 2Period 3Period 4
Security 10160200250
Security 230100470
2-year zero010000
3-year zero001000
Only the two zero-coupon bonds are tradable; Securities 1 and 2 define the liabilities.

HEDGING LOGIC

A parallel shift changes the present value of every remaining cash flow. The hedge therefore depends on both present value and duration.

Use the 2-year and 3-year zeros to offset the sensitivity of the non-tradable liability. The existing zero holding and cash differ by trader type, so the required trade is type-specific.

At year-end, all remaining positions are marked to the realized curve and converted to market cash.

GRADE CASH

Market cash <= 5,000: 0
Market cash >= 9,999: 10

Intermediate case formula:
5 + [(cash - 5,000)/(9,999 - 5,000)] x 5

Results accumulate across trials.