This paper argues that firms may not issue debt in order to avoid the adverse selection cost of debt. Theory suggests that since debt is a concave claim, it may be mispriced when outside investors are uninformed about firms’ risk. The empirical literature has however paid little attention the caveat that the “lemons” problem of external financing first identified by Myers (1984) only leads to debt issuance, i.e. a pecking order, if debt is risk free or, if it is risky, that it is not mispriced.