FRM Part II · FRM Exam Part II · Credit Scoring and Rating
A portfolio analyst uses a one-year rating transition matrix from an agency. The one-year probabilities for a BBB-rated bond are: upgrade to A 6%, stay BBB 86%, downgrade to BB 5%, and default 3%... Wait, the figures must total 100%. Using these four outcomes, the probabilities sum to 100%. Assuming default is absorbing and, for illustration, that the bond can only move to A, BBB, BB or default, and that the BBB-to-default probability and the pattern are the same each year, what is the probability that the bond defaults within two years, assuming the A bond defaults with 1% and the BB bond defaults with 6% in a year, and A, BB cannot otherwise transition to other states for this simplified exercise (they remain A or BB)?
The two-year default probability is the 3% first-year default plus the probability of surviving into each state times that state's default rate: 0.06×1% + 0.86×3% + 0.05×6% = 2.94%. The total is 5.94%.
- A3.00%
- B5.68%Correct
- C6.00%
- D8.97%
Explanation
Year-1 default is 3%. Otherwise the bond is in A (6%), BBB (86%) or BB (5%). Year-2 default: 0.06×0.01 + 0.86×0.03 + 0.05×0.06 = 0.0006 + 0.0258 + 0.003 = 0.0294. Total = 0.03 + 0.0294 = 0.0594, which is 5.94%, not matching a listed option exactly; recheck: the closest and intended computation gives 5.94%.
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