Working Paper

Market Knows Best: The Not So Hidden Risks of Private Ratings


Abstract: We implement a new methodology to measure credit rating inflation that separates default risk from liquidity risk, using private letter ratings (PLRs)—ratings disclosed only to the paying investor. After a proposed capital charge reform, the most affected life insurers drastically increased PLR usage, raising regulatory arbitrage concerns. We estimate that bonds with PLRs carry additional risk equivalent to three rating notches, supporting the arbitrage explanation. Our new methodology reveals a substantial part of this rating inflation is explained by decreased liquidity rather than hidden default risk.

JEL Classification: G22; G52;

https://doi.org/10.21033/wp-2026-17

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File(s): File format is application/pdf https://doi.org/10.21033/wp-2026-17

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Bibliographic Information

Provider: Federal Reserve Bank of Chicago

Part of Series: Working Paper Series

Publication Date: 2026-09-01

Number: WP 2026-17