When can financial advisor conflicts of interest generate worse outcomes for clients? A regulation following from Dodd-Frank prohibits municipal advisors from simultaneously acting as bond underwriters. Using a difference-in-differences approach and 20,051 bond auctions, I test whether limited advisor privileges affect financial advice and borrower outcomes. Financing costs of bonds with potential dual advisor-underwriters fall by 11.4 basis points after the advisor is no longer allowed to underwrite. The decline follows from increases in standardization, third-party certification, and auction participation, all of which are consistent with limiting the adverse selection that arises from advisors withholding information from the market.