Definition
Stress tests assess how a portfolio would perform under severe adverse conditions that VaR models may not capture. Historical scenarios replay past crises (2008 financial crisis, COVID crash, dot-com bust). Hypothetical scenarios model events like a sovereign default, oil price shock, or rapid rate rise. Regulators require banks to pass annual stress tests (CCAR/DFAST in the US).
lightbulb Example
Stress test a bond portfolio: what happens if the 10-year yield rises 200bps? Results: portfolio loses 14%, duration shortens to 5.8 years, and 3 positions breach covenant thresholds. Management can then decide whether to pre-emptively reduce exposure.
verified_user Key Points
- Tests extreme scenarios beyond normal VaR
- Historical: replay past crises
- Hypothetical: model plausible severe events
- Required by bank regulators (CCAR/DFAST)