Why duration matching matters
Institutions use it to stabilize surplus or funded status rather than merely minimize asset volatility. Matching market value and duration can immunize a simple liability against small parallel rate shifts.
How it is applied
Investors estimate liability cash flows and discount rates, calculate asset and liability duration and present value, select instruments, and rebalance as time, yields, and cash flows change. The investor estimates the duration of liabilities and constructs assets with similar interest-rate sensitivity, often also matching present value. Rebalancing is required as time passes, yields move, cash flows occur, and liability assumptions change. Key-rate duration can improve protection against nonparallel curve shifts.
Portfolio example
A pension liability has duration of 12 years. The plan combines bonds and derivatives so its liability-hedging assets have similar dollar duration. A pension liability has present value 100 million and duration 10 years. Assets worth 100 million with duration 10 have approximately matched first-order sensitivity. If assets are only 80 million, matching duration alone does not close the funding gap.
How to interpret it
Equal duration reduces first-order rate mismatch under stated assumptions. It does not mean the assets mature on the same date or that all liability risks are removed. When values and durations match, small parallel rate changes should affect assets and liabilities similarly. This reduces funded-status volatility rather than guaranteeing enough cash on every payment date. Cash-flow matching is a stricter but often costlier approach.
Limitations and common misconceptions
Nonparallel curve moves, convexity differences, inflation, credit spreads, longevity, cash-flow uncertainty, model changes, and rebalancing costs create residual risk. Convexity, curve twists, inflation, credit spreads, mortality, benefit changes, and model revisions create mismatch. Duration is a local approximation. Illiquid assets and derivatives also introduce collateral and rebalancing needs during stress. Governance should define tolerance bands and the action required when the match drifts. Derivatives can adjust duration efficiently but create collateral calls that the underlying liability model does not show. For complex obligations, match several key-rate durations and inflation sensitivity rather than one aggregate number. Surplus assets and contribution policy remain necessary when liabilities exceed asset value.
Sources and further reading
- Overview of Asset AllocationCFA Institute
- Portfolio Management for Institutional InvestorsCFA Institute