This paper studies simultaneous multilateral search (SMS) in over-the-counter markets: When searching, a customer simultaneously contacts several dealers and trades with the one offering the best quote. Higher search intensity (how often one can search) improves welfare, but higher search capacity (how many dealers one can contact) might be harmful. When the market is in distress, customers might inefficiently favor bilateral bargaining (BB) over SMS. Such a preference for BB speaks to the sluggish adoption of SMS trading, like request-for-quote protocols, in over-the-counter markets. Furthermore, a market-wide shift to SMS may not be socially optimal.

Collateral frictions have a profound effect on our economic landscape, ranging from the design of financial securities, laws, and institutions, to various rules and regulations. We analyze a model with disagreement, where securities and collateral requirements are endogenous. It shows that the security that isolates the variable with disagreement is “optimal” in the sense that alternative securities cannot generate any trading. In an economy with N states, investors may introduce more than N securities, and markets are still incomplete. The model has several novel predictions on the behavior of basis—the spread between the prices of an asset and its replicating portfolio.