This paper investigates how dealers’ trading relations shape their trading behavior in the corporate bond market. Dealers charge lower spreads to dealers with whom they have the strongest ties and more so during periods of market turmoil. Systemically important dealers exploit their connections at the expense of peripheral dealers as well as clients, charging higher markups than to other core dealers. Also, intermediation chains lengthened by 20% following the collapse of a flagship dealer in 2008 and even more for institutions strongly connected to this dealer. Finally, dealers drastically reduced their inventory during the crisis.

Agency mortgage‐backed securities (MBS) trade simultaneously in a market for specified pools (SPs) and in the to‐be‐announced (TBA) forward market. TBA trading creates liquidity by allowing thousands of different MBS to be traded in a handful of TBA contracts. SPs that are eligible to be traded as TBAs have significantly lower trading costs than other SPs. We present evidence that TBA eligibility, in addition to characteristics of TBA‐eligible SPs, lowers trading costs. We show that dealers hedge SP inventory with TBA trades, and they are more likely to prearrange trades in SPs that are difficult to hedge.