登录之后可查看解析

If a firm is financed with 100% equity, there is a direct relationship between changes in the firm’s ROE and changes in operating income. Adding financial leverage (debt) to the firm’s capital structure will cause ROE to become much more volatile and ROE will change more rapidly for a given change in operating income. The increased volatility in ROE reflects an increase in both risk and potential return for equity holders. Note that financial leverage results in increased default risk, but since existing bond holders are compensated by coupon interest and return of principal, their potential return is unchanged. Although financial leverage will generally increase ROE if a firm has a positive operating margin (EBIT/Sales), if the operating margin were small, the added interest expense could turn the firm’s net profit margin negative, which would in turn make ROE negative.