Before revision: We use a model of proportionate growth to describe the dynamics of international trade flows. We provide an explanation to the fact that the extensive margin of trade account for a large fraction of the greater exports of large economies, as well as for a number of stylized facts described by the literature on trade networks such as the power-law distribution of connectivity and the fat tails displayed by the distribution of  the growth rates of trade flows.
After revision: We develop a simple theoretical framework for the evolution of weighted network that is consistent with a number of stylized features of real-world data. In our framework, the fat tails displayed by the distribution of the growth rates of trade flows.