We derive a closed form solution for the valuation of risky discount debt when interest rates
are stochastic. We extend Merton's [1974] approach to risky discount debt valuation under
constant interest rates to the stochastic interest rate environment of Vasicek [1977]. Business
risk is modelled as a geometric Brownian motion that is correlated with interest rates. We
derive and explore the relationship between the credit premium and the term premium of
corporate debt. In a banking environment, the results can also be applied to analyze (a) the
allocation of capital to banking activities of varying credit risk and interest rate risk, (b) the
measurement of relative capital adequacy when compared to peer banks, and (c) the interest
rate risk-minimizing funding strategy.