Stress Testing
Stress testing is re-running a loan's or a portfolio's numbers under deliberately adverse assumptions to find what breaks, and at what point.
What stress testing is for
A loan underwritten at a 1.29x DSCR and 65 percent LTV looks safe on the day it closes. Stress testing asks what has to happen for that to stop being true, and whether the answer is plausible inside the loan term.
Regulators expect institutions with meaningful CRE concentrations to test both individual credits and the portfolio. The exercise is also straightforwardly useful: it converts a set of ratios into a statement about what the institution can absorb.
Scenarios lenders commonly run
- Interest rate shock. Re-underwrite at a rate 200 to 300 basis points above the contract rate, or at the rate implied at maturity, and see where coverage lands.
- Vacancy and rent decline. Reduce occupancy or in-place rents by a stated percentage and recompute NOI and coverage.
- Cap rate expansion. Widen the exit cap rate and recompute value and LTV at maturity. This is the test that catches refinance risk a current LTV hides.
- Expense inflation. Insurance and property taxes have moved sharply in several markets, and both are largely outside the borrower's control.
- Tenant loss. On single-tenant or anchor-dependent properties, model the space going dark including re-tenanting cost and downtime.
At portfolio level
The same scenarios run across the book, sliced by property type, geography, sponsor, and maturity year. The output that matters is usually concentration: how much of the portfolio fails a given test at once, and whether the failures cluster in the same quarter of the same year.
A maturity wall is the reason. Loans originated in the same vintage at similar terms come due together, and they meet the market in whatever condition it is in that year.
What to do with the results
Stress results feed loan structure (reserves, covenants, recourse, amortization), portfolio limits, allowance methodology, and the timing of borrower conversations. A loan identified two years early as likely to fail a refinance test is a workout conversation with options. The same loan identified at maturity is a problem.