The model developed in the article helps price securities that are affected by stock market, interest rate, and default risks at the same time. It uses observable data like stock prices and interest rates, rather than hidden processes. The model combines different models to show how stock prices, default risks, and interest rates are related. By using a simple lattice structure, the model can be easily applied to real market data and used to predict default probabilities. The model can also be expanded to handle related default risks and value various financial products like convertible bonds and debt swaps. When applied to a credit default index, the model shows that stock market performance can explain credit risk.