Asset encumbrance, bank funding and fragility

We model asset encumbrance by banks subject to rollover risk and study the consequences for fragility, funding costs, and prudential regulation. A bank's privately optimal encumbrance choice balances the benefit of expanding profitable yet illiquid investment, funded by cheap long-term senior secured debt, against the cost of greater fragility from runs on unsecured debt. We derive testable implications about encumbrance ratios. The introduction of deposit insurance or wholesale funding guarantees induces excessive encumbrance and fragility. Ex-ante limits on asset encumbrance or ex-post Pigovian taxes eliminate such risk-shifting incentives. Our results shed light on prudential policies currently pursued in several jurisdictions.