This paper shows that supply shock uncertainty interacts with the monetary policy rule to drive bond risks in a New Keynesian asset pricing model. In my model, positive nominal bond-stock betas emerge as the result of volatile supply shocks but only if the monetary policy rule features a high inflation weight. Habit formation preferences generate endogenously time-varying risk premia, explaining the volatility and predictability of bond and stock excess returns in the data, and implying that bond-stock betas price the expected equilibrium mix of shocks rather than realized shocks. The model explains the change from positive nominal and real bond-stock betas in the 1980s to negative nominal and real bond-stock betas in the 2000s with a shift from dominant supply shocks and an inflation-focused monetary policy rule, to demand shocks in the 2000s. Post-pandemic nominal and real bond-stock betas are explained with dominant supply shocks and a late increase in the monetary policy inflation coefficient.

We show that endogenous variation in risk aversion over the business cycle can jointly explain financial market responses to high-frequency monetary policy shocks with standard asset pricing moments. We newly integrate a work-horse New Keynesian model with countercyclical risk aversion via habit formation preferences. In the model, a surprise increase in the policy rate lowers consumption relative to habit, raising risk aversion. Endogenously time-varying risk aversion in the model is crucial to explain the large fall in the stock market, the cross-section of industry returns, and the increase in long-term bond yields in response to a surprise policy rate increase.

The frequency with which firms adjust output prices helps explain persistent differences in capital structure across firms. Unconditionally, the most flexible-price firms have a 19% higher long-term leverage ratio than the most sticky-price firms, controlling for known determinants of capital structure. Sticky-price firms increased leverage more than flexible-price firms following the staggered implementation of bank deregulation across states and over time, which we use in a difference-in-differences strategy. Firms’ frequency of price adjustment did not change around the deregulation.