というNBER論文が上がっている（ungated版）。原題は「Bank Runs, Fragility, and Regulation」で、著者はManuel Amador（ミネソタ大）、Javier Bianchi（ミネアポリス連銀）。
以下はその要旨。
We examine banking regulation in a macroeconomic model of bank runs. We construct a general equilibrium model where banks may default because of fundamental or self-fulfilling runs. With only fundamental defaults, we show that the competitive equilibrium is constrained efficient. However, when banks are vulnerable to runs, banks’ leverage decisions are not ex-ante optimal: individual banks do not internalize that higher leverage makes other banks more vulnerable. The theory calls for introducing minimum capital requirements, even in the absence of bailouts.
（拙訳）
我々は銀行取り付け騒ぎのマクロ経済モデルで銀行規制を調べた。我々は、ファンダメンタルもしくは自己実現的な銀行取り付け騒ぎのせいで銀行が債務不履行に陥る可能性のある一般均衡モデルを構築した。ファンダメンタルな債務不履行だけの場合には、競争均衡が制約付きで効率的であることを我々は示す*1。しかし、銀行が取り付け騒ぎに対して脆弱だと、銀行の債務の決定は事前最適ではない。即ち、個々の銀行は、負債の増加が他の銀行をより脆弱にすることを内部化しない*2。理論上は、救済が無い場合でも、最低限の必要資本の導入が要求される*3。
*1:導入部では「Our analysis compares the competitive equilibrium with the solution of a constrained social planner problem that chooses borrowing decisions on behalf of banks in the initial period to maximize banks’ ex-ante welfare. In this constrained-efficient allocation, banks retain the ability to default in the intermediate and final periods, and the price of capital clears the capital market in each period. The critical distinction between the constrained-efficient allocation and the competitive equilibrium is that the planner internalizes how the amount of borrowing in the initial period affects the prices of capital and, in turn, affects the continuation values for banks. In the first part of the paper, we provide welfare theorem-like results in the model where bank runs cannot happen, although banks may still default because of fundamentals. We show that competitive equilibria are constrained efficient, and establish the existence and uniqueness of a competitive equilibrium.」と説明している。
*2:導入部では「The crux of the mechanism is as follows: when banks face runs, they are net sellers of assets because they need liquidity to repay the deposits that are being withdrawn. With higher aggregate bank equity, asset prices remain elevated, making it easier for banks to access liquidity during runs. However, because banks do not account for these positive general equilibrium effects, they take on too much leverage from a social point of view.」と説明している。
*3:結論部では「Echoing previous debates following the Great Financial Crisis of 2008, many proposals for tightening banking regulation are aimed at preventing bank bailouts. In our model, raising banks’ capital requirements is desirable even in the absence of such bailouts. The basic message is that leverage and financial distress result in lower asset prices, and in turn, low asset prices make the economy more vulnerable to the damaging effects of self-fulfilling bank runs.」と説明している。
