A portfolio based theory of excessive foreign borrowing and capital control in a small open economy

We develop a simple model of portfolio choice in a mean variance framework to address the issue of international borrowing and financial crisis. Instead of adverse selection or moral hazard of lending and borrowing activities we emphasise the role of exchange rate movement. Syndicated borrowing by way of internalising the aggregate effect tends to restrict excessive borrowing from external source. However, this may undermine the welfare consequences by further aggravating the extent of risk undertaken in the process. There is a built-in externality in the model that leads to over exposure to foreign currency debt and readily calls for intervention by the government. Government intervention by way of a tax on foreign borrowing may help restrain the amount of external debt and implement the first best.