Banks, Market Organization, and Macroeconomic Performance: An Agent-Based Computational Analysis∗

This paper is an exploratory analysis of the role that banks play in supporting what Jevons called the “mechanism of exchange.” It considers a model economy in which exchange activities are facilitated and coordinated by a self-organizing network of entrepreneurial trading firms. Collectively, these firms play the part of the Walrasian auctioneer, matching buyers with sellers and helping the economy to reach prices at which peoples’ trading plans are mutually compatible. Banks affect macroeconomic performance in this economy because their lending activities facilitate the entry and influence the exit decisions of trading firms. Both entry and exit have ambiguous effects on performance, and we resort to computational analysis to understand how they are resolved. Our analysis draws an important distinction between normal and worstcase scenarios, with the economy experiencing systemic breakdowns in the latter. We show that banks can provide a “financial stabilizer” that more than counteracts the familiar financial accelerator, and that the stabilizing role of the banking system is particularly apparent in worst-case scenarios. In line with this result, we also find that under less restrictive lending standards banks are able to more effectively improve macroeconomic performance in the worst-case scenarios.