Capital adequacy has become the main regulatory tool to achieve financial stability in the last twenty years. While most papers analysed the effect of capital adequacy on risk taking, there is a lack of evidence on the relationship between deleveraging and the return on equity capital. In this paper, we examine the evolution of the banking system in Japan over the period 2000–16, where the re-capitalization issue has already played a major role in policy making. Specifically, we estimate the shadow return on equity capital for both listed and unlisted banks by measuring the loans-funding-equity technology through the dual cost function, controlling for risk exposure and bad loans, and accounting for both the standard asset-based model of bank outputs, and income-based model. Such an approach is likely to be important if the central bank permits banks with unsustainable balance sheets to continue in existence, and we refer to this as zombie banking. Overall, our results show that deleveraging did reduce the shadow return on equity for the City banks. We also find that that the presence of ‘zombie’ banks was concentrated and large among the smaller less diversified Regional Banks.

资本充足率已成为过去二十年来实现金融稳定的主要监管工具。虽然大多数论文分析了资本充足率对风险承担的影响，但缺乏关于去杠杆化与股本回报率之间关系的证据。在本文中，我们考察了日本银行体系在 2000-16 年期间的演变，其中资本重组问题已经在政策制定中发挥了重要作用。具体而言，我们通过双重成本函数衡量贷款-融资-股权技术，控制风险敞口和不良贷款，并同时考虑标准资产模型，估计上市银行和非上市银行的股权资本影子回报率。银行产出和基于收入的模型。如果中央银行允许资产负债表不可持续的银行继续存在，这种方法可能很重要，我们将其称为僵尸银行。总体而言，我们的结果表明，去杠杆确实降低了城市银行的影子股本回报率。我们还发现，“僵尸”银行的存在集中在规模较小、多元化程度较低的区域银行中。