A Monetary Policy Asset Pricing Model

We propose a model where monetary policy is the key determinant of aggregate asset prices (financial conditions). Spending decisions are made by a group of agents ("households") that respond to aggregate asset prices, but with noise, delays, and inertia. Asset pricing is determined by a different group of forward-looking agents ("the market"). The central bank ("the Fed") targets asset prices to close the output gap. Our model explains several facts, including why the Fed stabilizes asset price fluctuations driven by financial market shocks ("the Fed put/call"), but destabilizes asset prices in response to aggregate demand or supply shocks that induce macroeconomic imbalances (as in the late stages of the Covid-19 recovery). Although the Fed targets asset prices, it "cooperates" with the market to achieve its desired asset price. When the market and the Fed have different beliefs, the market perceives monetary policy "mistakes" that influence the policy rate the Fed needs to set. These perceived "mistakes" induce a policy risk premium and may generate a "behind the curve" phenomenon