Collateral plays an important role in supporting a vast range of transactions that help ensure the efficient functioning of the financial system. But collateral markets also have the potential to exacerbate risks to financial stability, not least given that, during periods of market stress, demand for high-quality collateral may increase, while collateral availability may fall. This paper offers a means to estimate how this potential imbalance between collateral supply and demand is likely to vary as a function of market stress. In addition, it offers an estimate of the increase in market volatility sufficient to cause a dislocation in the market for collateral and a subsequent deterioration in market functioning. It suggests that, from the perspective of financial stability, the implications of an imbalance between the supply and demand of collateral are likely to be comparatively benign, but that a reduction in the willingness and/or ability of market participants to act as intermediaries in collateral markets is likely to have more serious consequences for market functioning. This work also provides a framework through which policy makers can investigate how regulations might affect the proximity of these risks.