An assumed equity rise, lower yields and narrower spreads used as a directional comparison. Are the reported sensitivities consistent when the shock changes sign?
| Assumption | Change | Convention |
|---|---|---|
| Equities | 15.00% | Beta times broad equity shock |
| Government rate | -75 bp | Parallel shift |
| Credit spread | -50 bp | Additive spread-duration effect |
| EUR | 5.00% | USD value of one local currency unit |
| GBP | 5.00% | USD value of one local currency unit |
| JPY | 3.00% | USD value of one local currency unit |
Frozen reference result
The documented $10 million example gives a modeled P/L of $879,531.25 and contribution of 8.80%. All example holdings are mapped; this is not a result for your portfolio.
| Holding | Local change | USD change | P/L |
|---|---|---|---|
| US equities | 15.00% | 15.00% | $600,000.00 |
| Treasury sleeve | 5.42% | 5.42% | $162,562.50 |
| Corporate bonds | 5.85% | 5.85% | $116,968.75 |
| Cash reserve | 0.00% | 0.00% | $0.00 |
A positive control for the adverse scenarios
The purpose of this preset is directional comparison. Positive-beta equity should rise with the assumed equity market; positive-duration bonds should benefit from lower yields; positive spread duration should benefit from tighter spreads. The resulting gain checks how the chosen exposures behave when several assumed pressures ease together.
These are hypothetical conditions, not observations of a recovery or a forecast of policy easing. The preset has no assigned probability and is not the exact sign reversal of another scenario. Its favorable result cannot be averaged with adverse results to claim an expected return without a separately justified probability model.
Convexity makes equal rate shocks asymmetric
For the reference Treasury sleeve, a 75 basis point rate decline gives 5.25% through duration plus 0.16875 percentage points through convexity, totaling 5.41875%. A separate, rate-only 75 basis point rise would instead produce a 5.08125% loss. Both calculations keep duration seven and convexity 60 unchanged.
The squared rate term explains that asymmetry: it remains positive when the shock changes sign. FINRA's duration discussion notes that bond responses need not be symmetric and that redemption features matter [1]. This engine's fixed, nonnegative convexity is an approximation, not full repricing of those features.
A favorable bond mark can overstate an option-bearing gain
The SEC identifies call risk when an issuer retires debt early, potentially following a rate decline [2]. The calculator does not exercise calls, accelerate mortgage repayments or shorten duration during a rally. A callable or prepayable holding should not inherit the example's upside merely because it is labelled a bond.
Spread tightening adds a separate linear benefit, with no spread convexity or interaction with rates. Starting yield and spread levels are absent, so the engine cannot check whether the assumed decreases imply sensible ending levels. Those checks require instrument data beyond the change inputs, even when every input passes validation.
Currency appreciation compounds the upside
For an illustrative EUR equity holding at beta one, a 15% local gain and 5% currency appreciation combine into a 20.75% USD gain. Multiplying 1.15 by 1.05 preserves the interaction. The default USD holdings do not receive that additional benefit, regardless of the foreign-currency assumptions shown above.
This arithmetic tests translation direction, not the success of a currency hedge. The engine has no hedge contracts, foreign revenue model or changing equity beta. Likewise, USD cash remains unchanged because income is excluded; its zero contribution is not evidence that an actual cash account would earn nothing over time.
Do not confuse a comparison with a recovery path
A 15% gain does not undo a preceding 30% loss: 0.70 times 1.15 leaves 80.5% of the original value. More importantly, the preset comparison starts each scenario from the same holdings. It does not apply relief to the ending positions of an adverse scenario or simulate rebalancing between them.
Use the favorable case to question signs, units and unusually large sensitivity-driven gains, then compare nonlinear holdings with independent repricing. Keep capital gains separate from coupon income, refinancing effects and realizable sale proceeds. A reassuring positive total cannot validate the adverse scenarios, establish liquidity or measure the likelihood of recovery.
Review checkpoints
- Use relief as a directional comparison, not an expected-return estimate or exact inverse scenario.
- Positive convexity creates unequal results for equal upward and downward rate changes.
- Check calls, starting yield levels and sequential-return arithmetic outside the fixed-sensitivity result.
Source notes
Continue the analysis
How to Define Scenario Severity
Separate shock size, joint plausibility, duration, and portfolio impact when building a transparent severity ladder.
Challenge the model, not just its arithmetic
Separate implementation tests from economic validation, construct informative challengers, and document unresolved limitations and permitted uses.
Where duration and convexity stop explaining the loss
Audit rate-shock units, duration conventions, curve shape, embedded options, and the gap between approximations and bond revaluation.
First edition, 16 October 2026. Hypothetical values are teaching inputs, not observed portfolio or provider results.