This paper offers a dynamic model of opaque over-the-counter markets. A seller searches for an attractive price by visiting multiple buyers, one at a time. The buyers do not observe contacts, quotes, or trades elsewhere in the market. A repeat contact with a buyer reveals the seller's reduced...

Market models that have worked well for years can suddenly fail dramatically, such as during the financial crisis of the late-2000s. For example, models that assigned credit ratings to mortgage-backed securities (MBS) predicted relative default rates well for decades. It was only in the...