The share of secured debt issued (as a fraction of total corporate debt) declined steadily in the United States over the twentieth century. This stems partly from financial development giving creditors greater confidence that high-quality borrowers will respect their claims even if creditors do not obtain security upfront. Consequently, such borrowers prefer retaining financial flexibility by not giving security up front. Instead, security is given contingently—when a firm approaches distress. This also explains why, superimposed on the secular decline, the share of secured debt issued is countercyclical.

中文翻译：

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担保债务的减少

二十世纪，美国发行的担保债务份额（占公司债务总额的比例）稳步下降。这在一定程度上源于金融发展让债权人更有信心，即使债权人没有预先获得担保，优质借款人也会尊重他们的债权。因此，此类借款人更愿意通过不预先提供担保来保持财务灵活性。相反，当一家公司陷入困境时，安全感是偶然提供的。这也解释了为什么在长期下降的情况下，发行的担保债务份额是反周期的。