Contagion in the interbank market: Funding versus regulatory constraints

The contagion potential of mark-to-market accounting rules interacting with regulatory constraints is compared to that of funding constraints in a network of banks. The fair value accounting rules were amended at the height of the crisis to break the vicious link between allegedly irrational market prices and regulatory constraints. Anecdotal evidence from the recent crisis suggests that funding constraints posed more serious problems to banks than regulatory constraints. Simulation results show that, for low equity and high levels of short-term debt relative to liquid asset holdings, the contagion potential arising due to funding constraints is higher than the one due to accounting induced regulatory constraints. Allowing balance sheet valuation to affect the expectations about future insolvency, and implicitly, the roll-over decision of short-term creditors, can mitigate or amplify systemic risk depending on which contagion channel is dominating. These results could be interesting for a regulator wishing to achieve a trade-off between transparency, the main goal of fair value accounting, and financial stability.