In a wholly synthetic bond portfolio, the largest valuation differences arise from refinancing needs rather than headline debt totals. Companies required to replace 40% of their borrowing within 18 months face a different cash-flow problem from peers with longer maturities. The exercise assumes an identical operating outlook, allowing the effect of debt timing to stand apart from changes in sales.

Under an illustrative refinancing rate increase of 1 percentage point, the short-maturity group spends an additional $12 million annually on interest for each $1.2 billion replaced. That arithmetic helps explain why maturity schedules can move relative valuations before earnings change. These are invented inputs, not live prices or forecasts; the analytical lesson is to distinguish the cost of existing debt from the cost of renewing it.