I've been trying to calculate the credit spread of a financial institution with a Fitch rate of A.
By using the transition matrix (https://www.fitchratings.com/web_content/nrsro/nav/NRSRO_Exhibit-1.pdf page 4), I obtained a default probability at 10 years
of 0.7941%
(by multiplying the matrix with itself 10 times).
After that, I tried to obtain the credit spred with a 40% of recovery rate with the following formula:
$$ PD = 1 - EXP(\frac{-spread \cdot years}{1-R}) $$
But I obtained a spread of 4,783
at 10 years which is very low to 100 bps
of credit spread obtained from a JP Morgan CDS. Results make more sense if I don't use the years in the formula, but I think they should be considered.