Metro Bank UK loan risk-weighting software error
UK challenger bank Metro Bank disclosed it had understated the risk-weighting, and therefore the capital requirements, of a category of commercial loans for years, wiping out nearly 40% of its share price in a single day.
The damage was public. The root cause was preventable.
UK challenger bank Metro Bank disclosed it had understated the risk-weighting, and therefore the capital requirements, of a category of commercial loans for years, wiping out nearly 40% of its share price in a single day.
What the software actually got wrong
A software and methodology error had been misclassifying certain commercial loans into a lower risk-weighting category than they should have received under regulatory rules for several years before internal reviewers caught the discrepancy.
A software and methodology error had been misclassifying certain...
A software and methodology error had been misclassifying certain commercial loans into a lower risk-weighting category than they should have received under regulatory rules for several years before internal reviewers caught the discrepancy.
Requs AI Edge Case flags this exact pattern at the requirements and architecture stage — before a single line of code implementing it exists — so the assumption behind it gets challenged while it is still cheap to fix.
Beyond code coverage and "shall" testing
Root causes like this one rarely show up in code coverage or requirements-compliance testing, because nobody wrote a requirement anticipating the specific edge case that broke. Requs AI Edge Case and Requs AI Software FMEA are built to surface exactly this class of overlooked failure mode — before the software is written.
Surfaces this before code exists
Identifies edge cases like this one at requirements and architecture time, using the Common Defect Enumeration to catalog failure patterns seen across hundreds of real-world software failures — including this one.
Connects the failure mode to the hazard
Traces this class of root cause directly to the system-level hazard it can produce, so a defect pattern like this one gets flagged during design review instead of after it ships.
Find the overlooked root causes before they ship.
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