This paper provides new insights on the way in which the capital structure and market power and capital structure and profitability are related. We predict and show that capital structure and market power, as measured by Tobins Q, have a cubic relationship. That is, at lower and higher ranges of Tobins Q, firms employ higher debt, and reduce their debt at intermediate range. This is due to the complex interaction of the market conditions, agency problems and bankruptcy costs. We also show saucer-shaped relation between capital structure and profitability because of the interplay of agency costs, costs of external financing and debt tax shield. To our knowledge, we are the first to uncover these results.