This paper shows that collateralized short-term debt, although privately optimal for reducing borrowers’ risk-taking incentives, can induce fragility (multiple equilibria). Despite sequential-service property being absent in collateralized debt, such as repurchase agreements, a systemic run can arise, featuring large increases in default risks, fire-sale discounts of collateral, cost of credit, and amount of credit rationing. Asset price guarantees, leverage caps, and central clearing promote stability and welfare. Using global games techniques, I show that a systemic run is more likely in bad times, and a large enough asset price guarantee reduces run risks.

We analyze a tractable rational expectations equilibrium model with margin constraints. We argue that constraints affect and are affected by informational efficiency, leading to a novel amplification mechanism. A decline in wealth tightens constraints and reduces investors’ incentive to acquire information, lowering price informativeness. Lower informativeness, in turn, increases the risk borne by financiers who fund trades, leading them to further tighten constraints faced by investors. This information spiral leads to (a) significant increases in risk premium and return volatility in crises, when investors wealth declines, (b) complementarities in information acquisition in crises, and (c) complementarities in margin requirements.