Learn / Risk & ALM
Interest-rate hedging
A hedge is a position added so that a market move hurts the book less. Hedging is not the same as guessing the next move in rates. You name the exposure, pick an instrument that offsets it, measure how much of the exposure closed, and keep watching what is left.
The classroom book is the same one as the insurance lesson. Assets $100 million, duration 6. Liabilities $100 million, duration 12.
01
Why the gap is the exposure
If assets and liabilities had the same dollar sensitivity to a parallel rate move, a parallel move would change both sides by about the same number of dollars. Surplus would barely move. They do not match. Assets move about $60,000 per basis point. Liabilities move about $120,000 per basis point. The book is short about $60,000 per basis point of parallel duration.
A rate decline is the painful parallel case for surplus. Liabilities, being longer, rise in value by more than the assets. Surplus shrinks. A rate rise does the opposite: the liabilities fall in value by more, and surplus grows. The hedge below is aimed at the shortfall of asset duration, not at a view that rates will rise.
02
Matching, immunization, and the swap
Duration matching means choosing assets, or a hedge, so the dollar duration of the assets lines up with the dollar duration of the liabilities. Cash-flow matching is stricter: the asset cash arrives in the same periods the liability cash is due. Immunization is the classic name for setting duration so a small parallel move leaves surplus about unchanged, with convexity watched as the second-order leftover.
A receive-fixed interest-rate swap lengthens the asset side. You receive 4% fixed and pay floating, on a notional sized so the swap’s dollar duration is about $60,000 per basis point. After that, a small parallel move changes the swap and the old gap by offsetting dollars. The notional itself is not a loan. The swap lesson shows why the $100 million stays put and only the interest nets are paid.
03
When the team reaches for something else
The receive-fixed swap obligates both sides for the remaining life. If the liability might change, or the hedge might not be wanted yet, that obligation is the wrong tool. A payer swaption is the right to pay fixed later. It spends a premium and keeps the choice. That is the swaption and the insurance ALM lessons. It does not lengthen assets today. It is a different job from the receive-fixed swap.
A cap pays the holder when a stated rate rises through a strike. A floor pays when a stated rate falls through a strike. A collar is a cap and a floor together. A Treasury future is a listed contract on a government bond, useful when the team wants a rate hedge that trades on an exchange. Each one changes rate exposure. None of them is a substitute sentence for the others.
04
Effectiveness and what remains
Hedge effectiveness, in this classroom, is how much of the $60,000 per basis point the hedge offset. A receive-fixed swap sized to $60,000 per basis point closes the parallel gap. Effectiveness against a parallel move is high. Effectiveness against a twist can still be poor, because the 2-year and the 30-year did not move together and the swap was not built as a set of key-rate hedges.
Dynamic hedging means adjusting that size as the book and the curve change, instead of setting one trade and walking away. Residual risk is the list of what the hedge did not cover: curve shape, credit, equity, volatility, liquidity, and the chance the liability cash flows change. Economic effectiveness is also not the same thing as the accounting result. That split is the economic risk and GAAP page.