Trading the Swap Agreement
Replicating a Custom Interest Rate Swap is a medium quant interview question on Fixed Income.
This question presents a fixed income derivative where two parties exchange a nonstandard combination of fixed and floating payments linked to a reference money-market rate. The candidate must interpret the custom payoff structure and express it as an equivalent portfolio of plain-vanilla interest rate swaps that could be traded in practice. The setting is typical of sell-side rates desks and structuring or risk roles, where one often needs to price or hedge bespoke agreements using liquid building blocks rather than trading the bespoke contract directly.
Conceptually, the problem leans on viewing swaps as linear instruments whose cash flows can be added and subtracted like algebraic terms. The candidate needs to manipulate the payoff expressions, group fixed and floating components, and recognize which side of each standard swap they are on. An interviewer is looking for fluent algebraic decomposition, comfort with interpreting "pay fixed / receive floating" versus the reverse, and a clear mapping from abstract cash flows to actual tradable swaps. Precision in sign conventions and an understanding of replication and hedging are key.
What it tests
Custom financial contracts can often be decomposed into linear combinations of standard instruments by algebraically combining their cash flow structures. The key is to express all payment obligations in terms of the same variables—such as a fixed rate and a floating rate—then group like terms. This works because swaps and similar derivatives are fundamentally additive: the net cash flow at each settlement is just the sum of each component's cash flow. By matching coefficients, you can identify how many standard contracts (and of what type) would replicate the custom contract's payoff. This principle holds because financial contracts are modular, and their linear payoffs allow for such decomposition without loss of generality.
Practise this question with written feedback, or hear it in a spoken mock interview.
Get started free