The interest rate at which US firms borrow funds has two features: (i) it moves in a countercyclical fashion and (ii) it is an inverted leading indicator of real economic activity: low interest rates forecast booms in GDP, consumption, investment, and employment. We show that a Kiyotaki-Moore model accounts for both properties when business-cycle movements are driven, in a significant way, by animal spirit shocks to creditfinanced investment demand. The credit-based nature of such self-fulfilling equilibria is shown to be essential: the dynamic correlation between current loanable funds rate and future aggregate economic activity depends critically on the property that the loan has a variable-rate component. In addition, Bayesian estimation of our benchmark DSGE model on US data 1975US data -2010 shows that movements in investment driven by animal spirits are quantitatively important and result in a better fit to the data than both standard RBC models and Kiyotaki-Moore type models with unique equilibrium.