The author received an email in 2011 about the S&P ratings downgrade of the US from AAA to AA+, citing concerns about fiscal challenges and political institutions. In 2023, Fitch also downgraded the US, leaving Moody's as the only agency with a top rating. However, in 2025, Moody's downgraded the US from Aaa to Aa1, citing the same reasons. The downgrade led to concerns about market reaction, but the author instead chose to discuss sovereign default risk, ratings agencies, and their biases and errors. Sovereign defaults have occurred throughout history, with foreign currency borrowing being a significant factor. Local currency defaults are persistent, and the consequences of default include economic and political implications, such as a negative impact on GDP, higher borrowing costs, and trade retaliation. Sovereign ratings are meant to measure default risk, but have limitations, such as being upward biased, exhibiting herd behavior, and being too little, too late. Ratings agencies draw on a multitude of data, including political and economic factors, but their ratings can be subjective. The performance of sovereign ratings is questionable, with default rates rising as ratings decline, but with caveats and limitations. The author concludes that sovereign ratings are not a perfect proxy for sovereign default risk.