A client with zero debt decides to issue debt to buy back equity. Assuming their business risk doesn't change, how would this recapitalization affect their WACC and the resulting DCF value?

一个完全没有负债的客户决定发债来回购股票（Recapitalization）。假设他们的基础业务风险不变，这种资本结构的改变会如何影响他们的WACC，以及最终的DCF估值？