We explain the ideas behind the valuation of options with early exercise features, so called American options. We also aim to clarify some popular misconceptions about when an American option should be exercised. These misconceptions seem to be prevalent among both academics and practitioners.

We show how to use 'uncertainty' in place of the more traditional Brownian 'randomness' to model a short-term interest rate. The advantage of this model is principally that it is difficult to show statistically that it is wrong. Whether the model is useful for pricing fixed-income products is...

Two of the authors (DE and PW) recently introduced a non-probabilistic spot interest rate model. The key concepts in this model are the non-diffusive nature of the spot rate process and the uncertainty in the parameters. The model assumes the worst possible outcome for the spot rate path when...

The modelling of credit risk, credit derivatives and non-hedgeable securities in general is currently in a poor state. Ideas from equity options theory have been adopted for credit risk, but have not been adapted for the peculiarities of this more complex world. This brief paper is a review and...