The yields on 10-year corporate bonds (with different ratings) and 10 year Treasury bonds are as follows: 10-year Corporate bond (AAA) = 2.72% 10-year Corporate bond (A)-3.64% 10-year Corporate bond (BBB) = 4.18% 10-year Treasury-bond - 1.72% The differences in these rates were probably caused primarily by: Real risk-free rate differences. Inflation differences O None of them Maturity risk differences Default and liquidity risk differences