A new model for pricing corporate bonds has been developed, taking into account the risks of credit rating changes and fluctuating interest rates. This model allows for multiple rating changes based on the company's financial health and considers how bond prices can jump when ratings change. The volatility of bond prices is also influenced by interest rate movements. The researchers used a mathematical formula to solve the model and found that it works well when interest rates follow a specific stochastic process. The model improves upon previous ones by allowing for more realistic rating changes and interest rate effects.