Investors faced yet another bumpy start to the trading week with US assets coming under fresh pressure, although it’s mounting concern over American debt rather than tariffs generating the volatility this time.

The move came as Republicans seek to approve a large package of tax cuts, spending hikes and safety-net reductions which could add trillions of dollars in U.S. debt.

After the United States lost its last perfect credit rating on Friday, Republicans and Democrats responded by pointing fingers at each other.

The downgrade of the U.S. sovereign credit rating Friday will likely mean higher borrowing costs on mortgages.

Investors sold U.S. government bonds and the dollar on Monday amid concerns about the U.S. fiscal picture. Stocks edged higher.

Investors sold stocks and bonds after Moody’s downgraded the U.S. credit rating, potentially complicating negotiations around Republicans’ tax plan.

Moody’s gave the U.S. a negative outlook—but markets didn’t flinch. This isn’t about default. It’s about trust, and why credibility erosion is the real risk.

Treasury yields fall and the dollar is little changed as Monday's "Sell America" trade recedes a bit. Concerns about the U.S. government debt flared up after the Moody's downgrade and the progress of a tax bill in Congress that looks poised to widen the already worrisome budget hole.

Wall Street is on edge about American investments again after receiving a significant warning about the safest of all safe havens: US debt.