The Moody’s announcement sent the yield on a 30-year Treasury bond to a high of 5.01% at one point on Monday. Bond yields rise as bond prices fall. When a selloff hits and demand for bonds dries up, it sends bond prices lower. In turn, bond yields move higher.

NBC News Senior Business Correspondent Christine Romans discusses Moody's decision to downgrade the U.S. credit rating and the Trump administration's posture on tariffs.

If the U.S.’s loss of its final perfect credit rating boosts yields on Treasury debt, it likely would boost the cost of borrowing for both companies and consumers.

Moody's downgrade of the U.S. sovereign credit rating late Friday appeared to have a modest impact on corporate bond market activity on Monday, as spreads widened slightly and new bond sales started the week softer than expected.

Moody resident calls for action as loose dog problem persists

Royal Caribbean Cruises Ltd. regained its investment-grade status on Monday after Moody’s Ratings upgraded the global cruise operator’s credit rating on a strong demand outlook and better credit metrics.

"Crypto is loving the Moody’s downgrade: Bitcoin is now 4% away from a new all time high and up over +40% since its April low. As the US Dollar weakens and uncertainty rises, Bitcoin and Gold are thriving. Instability is Bitcoin’s best friend," wrote the analysts at Kobeissi Letter.

American markets fell to open the week Monday, reacting to Saturday's news that Moody's Ratings was downgrading U.S. debt.