Does more leverage always worsen the debt agency problem? This paper presents a unified analysis that accounts for both risk-shifting and under-investment debt agency problems. For firms with positive marginal volatility of investment (defined as the change in cash flow volatility corresponding to a change of investment scale), equity holders' risk-shifting incentive will mitigate the under-investment problem. This implies that, contrary to conventional views, the total agency cost of debt does not uniformly increase with leverage. This model further predicts that, for high growth firms in which the under-investment problem is severe, the optimal debt ratio is positively related to the marginal volatility of investment. Empirical results support this prediction.

We develop a simply theory on interest rate swaps based on the difference between bank loans and public debts. While restrictive covenants of bank loans help reduce agency costs, banks also have natural disadvantages in bearing interest rate risk due to their floating liabilities. A firm that wants a fixed-rate loan can borrow a floating-rate loan from a bank and enter an interest rate swap to hedge the interest rate risk. Consistent with our theory, we find empirically that fixed-rate swap payers generally have lower credit ratings, higher leverage ratios, higher percentages of long-term floating-rate loans, and are more likely to use bank loans than floating-rate swap payers.

With the adoption of Regulation Fair Disclosure (Reg FD), market behavior around earnings releases displays no significant change in return volatility (after controlling for decimalization of stock trading) but significant increases in trading volume due to difference in opinion. Analyst forecast dispersion increases, and increases in other measures of disagreement and difference of opinion suggest greater difficulty in forming forecasts beyond the current quarter. Corporations increase the quantity of voluntary disclosures, but only for current quarter earnings. Thus, Reg FD seems to increase the quantity of information available to the public while imposing greater demands on investment professionals.