“…To derive , we extend the methodology in Orosi () by allowing non‐zero equity recovery at default. We start by observing that Equation gives the following equations for call option prices when To obtain analytic call option prices for apply the following transformations to the strikes and call option prices: Note that if the relation between c and x is given by or equivalently To ensure that the transformed call option prices, c , are decreasing and convex functions of x when …”