Answer: The probability that a AAA-rated bond defaults within one year is 0.00%

## Explanation **Option A is incorrect** because: - Looking at the transition matrix, the default probability for AAA-rated bonds is shown as **0.00%** in the "D" (Default) column - However, this doesn't mean the actual default probability is zero - it means that in the historical data sample, no AAA-rated bonds defaulted - In reality, even AAA-rated bonds have a non-zero (though very small) probability of default - The matrix shows historical frequencies, not theoretical probabilities **Analysis of other options:** - **Option B**: Correct - 7.37% is the transition probability from AAA to AA - **Option C**: Correct - 87.44% is the probability of remaining at AAA rating - **Option D**: Correct - 4.59% is the probability of becoming non-rated **Key insight**: Transition matrices are based on historical data and may not capture all possible outcomes, especially for rare events like AAA defaults.

Author: LeetQuiz Editorial Team