A classification of two-factor affine diffusion term structure models

Dai and Singleton (2000) introduced a typology of affine diffusion models when the domain of admissible values of the factors is an intersection of half planes and under some additional constraints on the parameters. This condition on the domain and the additional sufficient constraints are restrictive and can considerably diminish the practical interest of affine models. In this article we successfully address the research agenda sketched by Duffie, Filipovic, Schachermayer (2003, section 12.2, p. 1042). A systematic investigation is performed and our article provides a complete typology in the two-factor case, without prior restrictions on the domain and on the parameters.