We develop a model of voluntary disclosure and production decisions and use it to establish that firms will tacitly collude by disclosing when current market demand is low and when the decision horizon is long. Low demand helps sustain tacit collusion, because deviation from tacit collusion yields only a limited increase in profit when demand is low. Similarly, longer decision horizons give firms incentive to receive the benefits of collusion over a longer period. Using monthly production forecasts issued by the Big Three U.S. automobile manufacturers, we show that the frequency, horizon, and accuracy of the production forecasts increase when demand decreases and when the firms focus more on long-term profit. Collectively, the evidence suggests that firms use voluntary disclosures to tacitly collude. This paper was accepted by Brian Bushee, accounting.
