In a model where banks face a capital sufficiency requirement, we demonstrate that news about a fall in the expected return on a portfolio of international long bonds held by a bank leads to an immediate and persistent fall in economic activity. Even if the news never materializes, economic activity falls below steady state for several periods, followed by a recovery. The portfolio adjustment induced by the capital sufficiency requirements leads to a rise in loan rates and tighter credit conditions, which trigger the fall in activity. We contribute to the news-shock literature by showing that imperfect signals about future financial returns can create business cycles without relying on the usual suspects—shocks to technology, preferences, or fiscal policy—and to the emerging economy business cycle literature in that disturbances in world financial markets can cause domestic business cycles without shocks to the world interest rate or to country spreads.

In this paper we study the role of bank capital adequacy requirements in the transmission of aggregate productivity shocks. We identify a gap between the empirical and the theoretical work that studies the “credit crunch” effects of these requirements, and how they can work as a financial accelerator that amplifies business cycles. This gap arises because the empirical work faces some difficulties in identifying the effects of capital requirements, whereas the theory still lacks a structural framework that can address these difficulties. We bridge that gap by providing a general equilibrium theoretical framework that allows us to study this financial accelerator. The main insight we obtain is that the “credit crunch” and financial accelerator effects are rather weak, which confirms the findings of existing empirical work. Additionally, by developing a structural framework, we are able to provide an explanation for this result.

In contrast to recent successful developments in macro monetary policies, the modelling, measurement and management of systemic financial stability has remained problematical. Indeed, the focus of most effort has been on improving individual, rather than systemic, bank risk management; the Basel II objective has been to bring regulatory bank capital into line with the (sophisticated) banks‘ assessment of their own economic capital. Even at the individual bank level there are concerns over (i) appropriate diversification allowances, (ii) differing objectives of banks and regulators, (iii) the need for a buffer over regulatory minima, and (iv) the distinction between expected and unexpected losses (EL and UL). At the systemic level the quite complex and prescriptive content of Basel II raises dangers of ‘endogenous risk’ and procyclicality. Simulations suggest that this latter could be a serious problem.