Even before talk of fresh unfunded tax cuts took center stage in the budget wrangling on Capitol Hill, US bond investors were making their views loud and clear: If the government keeps spending more than it takes in,

Long-term US bond yields hit an 18-month high after Moody's last week downgraded the credit rating of the world's largest economy.

Treasury yield jumped more than 10 basis points, topping 5%, before easing just below that threshold by midday.

Moody's becomes latest major credit rating agency to downgrade US' 'perfect' long-term credit rating - Anadolu Ajansı

Markets came under pressure Monday as investors dumped stocks, U.S. bonds and the dollar — an unsettling trifecta — after the United States lost its triple-A bond rating on Friday.

Discover why SGOV remains a strong buy amid market volatility, steady Fed rates, and noise from US credit downgrades.

It all comes down to money. The credit rating is a guide to how risky buying debt is for potential investors. Independent agencies examine the metrics of a would-be bond seller to assess their creditworthiness and determine how likely that issuer might be to default on their debt.

Yields in the Treasury market are rising, threatening to make it more expensive for consumers and the U.S. to manage debt.