Pfd Company has debt with a yield to maturity of 7.2%, a cost of equity of 13.7%, and a cost of preferred stock of 8.8%. The market values of its debt, preferred stock, and equity are $ 10.6 million, $ 2.7 million, and $ 16.1 million, respectively, and its tax rate is 35 %. What is this firm's after-tax WACC? Note: Assume that the firm will always be able to utilize its full interest tax shield.