问题如下：
5. If Skylark implements Lee’s proposal to issue $1 billion of debt and use the proceeds to repurchase common shares, its weighted average cost of capital following the buyback will most likely:
选项：
A.increase to 8.50%.
B.increase to 8.70%.
C.decrease to 8.50%.
解释：
C is correct.
The WACC is the weight of debt times the after-tax cost of debt plus the weight of equity times the cost of equity. Skylark currently has a market value of $8 billion of equity and $2 billion of debt, for an 80/20 ratio. Using Exhibit 1, we find that this capital structure has a 5.5% pretax and 3.52% [5.5 × (1 – 0.36)] after-tax cost of debt and a 10.0% cost of equity. Thus the WACC equals (0.2 × 3.52) + (0.8 × 10.0) = 0.70 + 8.0 = 8.7%. After the buyback, Skylark’s capital structure will be 70/30, which results in a 6.0% pretax cost of debt (3.84% after tax) and a 10.5% cost of equity. Thus, the new WACC will be (0.3 × 3.84) + (0.7 × 10.5) = 1.15 + 7.35 = 8.5%, which is a decrease.
1.看了之前的解答，有一个地方我觉得不对，其中，资本结构是按照市场价格来计算的吧，这好像一级强调过，有市场价格用市场价格，而且题干表格里也是用的市场价格（之前解答说要用账面价格）。
2.多发债产生D*T不计入Equity吗？到底怎么处理呢？什么情况下需要计入，什么情况下忽略？
