This paper examines optimal corporate financing arrangements under asymmetric information for different patterns of temporal resolution of uncertainty in the underlying technology. An agency problem, a signalling problem and an agency-signalling problem arise as special cases. The associated informational equilibria and the optimal financing arrangements are characterized and compared. In the agency-signalling equilibrium the private information of corporate insiders at the time of financing is signalled through capital structure choices which deviate optimally from agency-cost minimizing financing arrangements, which in turn induce risk-shifting incentives in the investment policy. In the pure signalling case the equilibrium is characterized by direct contractual precommitments to implement investment policies which are riskier than pareto-optimal levels. Empirical implications for debt covenants and the announcement effect of investment policies and leverage increasing transactions on existing stock and bond prices are explicitly derived.