Metric

Parallel rate scenario

Definition

An interest rate scenario in which all points on the yield curve shift by the same amount simultaneously. The shape of the curve — the spread between short and long rates — remains unchanged.

What This Actually Means

Every maturity point moves by the same number of basis points — up 200bps, down 100bps, up 300bps. The curve shifts but does not twist or steepen. The six EBA prescribed scenarios include four parallel shocks (parallel up, parallel down, and two short rate shocks that are approximately parallel) alongside two non-parallel scenarios.

Where It Matters

Parallel scenarios are the workhorse of IRRBB measurement and the basis of the EVE supervisory outlier test. They are simple to apply, easy to compare across institutions, and — critically — easy for management to understand intuitively. A single number shift in rates is something a board or ALCO can grasp immediately without needing to understand yield curve dynamics. This makes parallel scenarios the natural language of risk appetite and limit frameworks.

For a well-hedged balance sheet, the parallel shock is typically the most severe scenario. When assets and liabilities are broadly matched in duration across the curve, a uniform shift in all rates hits both sides simultaneously and the net sensitivity is driven by any residual duration mismatch. This means that if a bank passes the parallel SOT comfortably, the parallel scenario has done its job as a stress test of overall duration positioning.

The limitation is that real rate cycles rarely produce parallel shifts — central bank policy changes typically move short rates sharply while long rates respond more slowly and by different amounts. A bank that looks well-hedged under a parallel scenario may be materially exposed to curve reshaping. Parallel scenarios should therefore always be run alongside non-parallel scenarios — relying solely on parallel shocks gives an incomplete picture of the true risk profile.

Related Terms

Non-parallel scenarios are less intuitive than parallel shocks — steepeners and flatteners require management to think about relative movements across different maturity points simultaneouslywhich is harder to communicate and harder to set risk appetite around. This is precisely why they tend to receive less attentionand why the risks they reveal are more likely to be hidden. The key diagnostic value of non-parallel scenarios: they detect structural mismatches that parallel shocks cannot see. A bank may show low EVE sensitivity under a parallel shift because its overall duration is broadly matched — but this can mask two equal and opposite risks sitting at different points on the curveeffectively netting each other out in a parallel scenario but both becoming loss-making in a curve reshaping. A steepener exposes one side of this hidden mismatch; a flattener exposes the other. Non-parallel scenarios are therefore not just additional stress tests — they are the tool for uncovering disguised concentrations of risk within an apparently hedged book. The steepener is particularly important for banks running large structural hedges: a steepening environment means the fixed rate received on long-dated swaps is locked in at a rate that looks low relative to where the short end has movedand NII from the hedge underperforms relative to the cost of short-term funding. The flattener stress-tests the opposite — short rates rising faster than long ratescompressing the margin on new business written at long-term fixed rates funded by short-term liabilities. Banks should not treat the two EBA prescribed non-parallel scenarios as sufficient — bespoke curve scenarios calibrated to the bank's specific balance sheet will typically reveal concentrations that the prescribed scenarios miss.
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