Credit spreads for secured debt are lower than for unsecured debt, especially when a firm's credit quality deteriorates, the economy slows, or average credit spreads widen. Yet investment-grade firms tend to be reluctant to issue secured debt at all times. In contrast, we find that for firms that are rated below investment grade, the likelihood of secured debt issuance increases as firm credit quality deteriorates, the economy slows, or average credit spreads widen. This differential pattern of issue behavior is consistent with highly rated firms seeing unencumbered collateral as a form of insurance, to be used only in extremis.

中文翻译：

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担保信用溢价和担保债务的发行

有担保债务的信用利差低于无担保债务，尤其是当公司的信用质量恶化、经济放缓或平均信用利差扩大时。然而，投资级公司往往不愿意在任何时候发行有担保的债务。相比之下，我们发现对于评级低于投资级别的公司，随着公司信用质量恶化、经济放缓或平均信用利差扩大，担保债务发行的可能性增加。这种发行行为的差异模式与高评级公司将无抵押抵押品视为一种保险形式一致，仅在极端情况下使用。