Margin spiral

Margin spiral is a self-amplifying feedback loop in which falling asset prices trigger margin calls, which force leveraged investors to sell assets, which drives prices lower, which triggers larger margin calls. It is the procyclical engine of market crises: the risk management that prevents individual defaults becomes the mechanism of systemic collapse. CCPs are particularly vulnerable to margin spirals because their margin models are calibrated to historical volatility and systematically underestimate tail risk during stress. When volatility spikes, CCPs demand more margin from all clearing members simultaneously, creating a correlated liquidity shock that no individual member's stress tests anticipated. The March 2020 Treasury market turmoil was a margin spiral in action: CCP margin requirements increased by hundreds of billions of dollars in days, forcing asset sales into already illiquid markets. The margin spiral reveals that collateral is not a buffer against risk but a transmitter of it — a mechanism that converts price volatility into funding volatility and distributes the shock across the entire cleared system.

The margin spiral is a specific instance of the broader Volatility paradox: the observation that risk-management frameworks calibrated to historical stability become sources of instability when the regime changes. The paradox suggests that the safer a system appears, the more vulnerable it becomes to rare events — not despite but because of its risk management.