Before revision:  Using self-financed strategy and duplication we are able to derive a Random Partial Differential Equation (RPDE) that any claim whose value depends on firm value and time should satisfy. We solve the RPDE for debt and loan guarantees under the assumption that there are no coupon payment nor dividends prior to the maturity of the debt.
After revision:  Using self-financed strategy and duplication we are able to derive a Random Partial Differential Equation (RPDE) that any claim whose value depends on firm value and time . Under specific final and boundary conditions, we solve the RPDE for debt and loan guarantees under the assumption that there are no coupon payment nor dividends prior to the maturity of the debt.