How stressful will Europe's bank stress tests prove? Investors won't have long to find out. The Committee of European Banking Supervisors, which is coordinating the tests, will on Wednesday publish details of which banks are being tested and what criteria will be used for the exercise.

Regulators are aware of the risks that insufficiently rigorous tests will inflame the volatile market situation rather than ease it. Even so, the tests are likely to disappoint investors in two key respects.