Previous studies show that conventional factors, such as firm-specific and macroeconomic variables, do a poor job of explaining yield spread changes. Using data from the US corporate bond market, this column shows that over-the-counter frictions explain around 23% in the variation of the common component and one third of the total variation in yield spread changes. The combination of search and bargaining frictions is slightly more important for the dynamics of yield spread changes than inventory frictions. The findings are broadly consistent with leading theories of intermediation frictions in over-the-counter markets.