This paper examines the investment and welfare effects of
a preferential trading area (PTA) on member and non-member countries
when countries differ in their relative size. I numerically solve a
three-country and two-good model to characterize equilibria
pertaining to investment diverting and creating effects of a
preferential trade area. I conclude that welfare benefits of a
preferential trade area are non-negative for the member countries,
and could go either way for the non-member countries depending on
their relative size. There exist equilibria which, given the
parameter values and the relative size, result in welfare
improvement in non-member countries