When market information such as price is difficult to communicate, consumers and firms may be unable to take advantage of mutually beneficial scale economies, so that coordination failures arise. Ostensibly uninformative advertising expenditures can be used to eliminate coordination failures, by allowing an efficient firm to communicate implicitly that it offers a low price. This provides a theoretical explanation for Benham's (1972) empirical association of the ability to advertise with lower prices and larger scale. Advertising becomes necessary for optimal coordination when the identity of the efficient firm is uncertain. An application to loss-leader pricing is developed.

We develop a theory of labor contracting in which negative productivity shocks lead to costly job loss, despite unlimited possibilities for renegotiating wage contracts. Such fragile contracts emerge from firms' trade-offs between robustness of incentives in ongoing employment relationships and costly specific investment. Contractual fragility can serve as a powerful mechanism for propagating underlying productivity shocks: in a simulated matching market equilibrium, i.i.d. shocks are greatly magnified in their effect on market output, and the effect is highly persistent. We also explore novel motivations for government policies that strengthen employment relationships.