We show how target debt ratios can improve the investment incentives in firms with risky debt outstanding and with asymmetric information. While profitable investments in a firm with risky debt and/or asymmetric information can reduce the value of existing equity, new debt offsets the value loss to old shareholders. Since financing a part of investments with new debt set by target debt ratios offsets wealth transfer effects, firms will not pass up valuable investment opportunities and will make the optimal investment decisions. For the effectiveness of target debt ratios, the new debt can be issued with shelf registration and can maintain the same priority as in the old debt.