The Price of Stability : Volatility and the Rise in Markups during the Great Moderation

During the Great Moderation, macroeconomic volatility declined while firm markups increased. We document a causal relationship between volatility and markups due to tacit collusion. We exploit the legalisation of interstate banking as an exogenous decrease in volatility. Using an instrumental variable approach, we show that a 1\% reduction in volatility causes a 19 percentage point increase in aggregate markups. The effect is due to large firms and firms operating in non-tradable industries. The changing market structure explains two-thirds of the effect, whereas reallocation only accounts for one-third. The reduction of volatility during the Great Moderation explains 31\% of the markup increase between 1980 and 1997