This paper seeks to inform about a feature of monetary policy that is largely overlooked, yet occupies a central role in modern monetary and financial systems, namely central bank collateral frameworks. Their importance can be understood by the observation that the money at the core of these...

The spread between unsecured and repo rates (collateral spread) fluctuates substantially and is negative on a significant portion of days. Recent theoretical work argues that collateral spreads are determined by a constrained-arbitrage relation between the unsecured rate, the repo rates, and the...

Repo rates frequently exceed unsecured rates in practice. As an explanation, this paper derives a constrained-arbitrage relation between the unsecured rate, the repo rate, and the illiquidity adjusted expected rate of return of the underlying collateral. The theory is based on unsecured...