Dealers in the over‐the‐counter municipal bond market form trading networks with other dealers to mitigate search frictions. Regulatory data show that this network has a core‐periphery structure with 10 to 30 hubs and over 2,000 peripheral broker‐dealers in which bonds flow from periphery to core and partially back. Central dealers charge investors up to double the round‐trip markups compared to peripheral dealers. In turn, central dealers provide immediacy by matching buyers with sellers more directly and prearranging fewer trades, especially during stress times. Investors thus face a trade‐off between execution cost and speed, consistent with network models of decentralized trade.

Fire sales induced by investor redemptions have powerful spillover effects among funds that hold the same assets, hurting peer funds' performance and flows, and leading to further asset sales with negative bond price impact. A one‐standard‐deviation increase in our fire‐sale spillover measure leads to a 45 (90) bp decrease in peer fund returns (flows) and a two percentage point increase in the likelihood of a large bond price drop. The results hold in a regression‐discontinuity design addressing identification concerns. Timing, heterogeneity, instrumental‐variable, and placebo tests further support the price‐impact mechanism. Model‐based counterfactual and stress‐test analyses quantify the financial stability implications.

We examine the network of trading relationships between insurers and dealers in the over‐the‐counter (OTC) corporate bond market. Regulatory data show that one‐third of insurers use a single dealer, whereas other insurers have large dealer networks. Execution prices are nonmonotone in network size, initially declining with more dealers but increasing once networks exceed 20 dealers. A model of decentralized trade in which insurers trade off the benefits of repeat business and faster execution quantitatively fits the distribution of insurers' network size and explains the price–network size relationship. Counterfactual analysis shows that regulations to unbundle trade and nontrade services can decrease welfare.