We show that firms intermediating trade have incentives to overinvest in financial expertise. In our model, expertise improves firms’ ability to estimate value when trading a security. Expertise creates asymmetric information, which, under normal circumstances, works to the advantage of the expert as it deters opportunistic bargaining by counterparties. This advantage is neutralized in equilibrium, however, by offsetting investments by competitors. Moreover, when volatility rises the adverse selection created by expertise triggers breakdowns in liquidity, destroying gains to trade and thus the benefits that firms hope to gain through high levels of expertise.