We propose a model of post‐Great Financial Crisis (GFC) money markets and monetary policy implementation. In our framework, capital regulation may deter banks from intermediating liquidity derived from holding reserves to shadow banks. Consequently, money markets can be segmented, and the scarcity of Treasury bills available to shadow banks is the main driver of short‐term spreads. In this regime, open market operations have an inverse effect on net liquidity provision when swapping ample reserves for scarce T‐bills or repos. Our model quantitatively accounts for post‐2010 time series for repo rates, T‐bill yields, and the Fed's reverse repo facility usage.

We provide a simple model of investment by a firm funded with debt and equity and empirical evidence to demonstrate that, once we control for the debt overhang problem with credit spreads, asset volatility is an unambiguously positive signal for investment, while equity volatility sends a mixed signal: Elevated volatility raises the option value of equity and increases investment for financially sound firms, but exacerbates debt overhang and decreases investment for firms close to default. Our study provides a simple unified understanding of the structural and empirical relationships between investment, credit spreads, equity versus asset volatility, leverage, and Tobin's .