Bank runs
银行挤兑
The ultimate price bubble collapse is a bank run. [Notes 1, 2] In a bank run, the relevant asset are cash deposits, where its primary role is as a store of value. To perform this role, depositors must believe that the bank’s assets have a value in excess of its liabilities. However, depositors are interested in the liquidation value of the bank’s assets, not just the value of the assets if they are held to maturity (being their "fundamental value"). To the extent the liquidation value is relevant, we can think of bank depositors as having “myopic rational expectations”.
It is usually the case that the bank’s assets are sufficient to settle the bank’s liabilities only if they are held to maturity, but not necessarily if they are liquidated. In this case, the depositors’ myopic rational expectations has multiple equilibria:
(“bank run”) Each depositor expects other depositors to withdraw their deposits immediately, forcing the bank to liquidate its assets; or
(“no bank run”) Each depositor expects other depositors to let their deposits remain with the bank, allowing the bank to hold its assets to maturity and settle any casual withdrawals of cash deposits.
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Note 1: In a bank run, the collapsed “price bubble” has a negative value, the market price of the bank’s assets falls below its fundamental value. Cash-at-hand becomes the preferred store of value; the “price bubble” switches from bank deposits to cash-at-hand.
Note 2: The true price bubble likely lies with the assets held by the bank. For example, loans given by the bank could be secured by assets (e.g., residential real estate) that are themselves valued above their fundamental value.
价格泡沫的典型破裂是银行挤兑。[注1，2] 在银行挤兑中，相关资产是现金存款，其主要作用是作为价值储存。要发挥这一作用，存款人必须相信银行的资产价格超过其负债。然而，存款人感兴趣的是银行资产的清算价值，而不仅仅是资产持有至到期时的价值（及其“基本价值”）。在清算价值相关的范围内，我们可以认为银行存款人具有“短视的理性预期”。
通常情况下，银行的资产只有在持有至到期时才足以清偿银行的负债，但如果这些资产被清算则不一定如此。在这种情况下，存款人的短视理性预期具有多重均衡：
（“银行挤兑”）每个存款人都期望其他存款人立即提取存款，从而迫使银行清算其资产；或
（“无银行挤兑”）每个存款人都期望其他存款人将他们的存款留在银行，从而允许银行持有其资产直至到期并结算任何随意的提取的现金存款。
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注1: 在银行挤兑中，破裂的“价格泡沫”具有负值，银行资产的市场价格跌至其基本价值以下。现金成为首选的价值储存手段；“价格泡沫”从银行存款转向手头上的现金。
注2: 真正的价格泡沫可能在于银行持有的资产。例如，银行发放的贷款可能由本身价格高于基本价值的资产（例如住宅地产）担保。