The US Treasury moved on Wednesday to calm a bond market rattled by surging borrowing costs, doubling the size of its debt buybacks hours before separate figures confirmed that the national debt had climbed past $40 trillion (€34.4tn) for the first time.

The federal debt reached $40 trillion as the government adds red ink at a rapid rate. That's leading nervous investors to demand higher interest rates —pushing up borrowing costs…

Federal debt has mounted amid tax cuts and trillions in pandemic spending, adding to the nation's interest payments.

The national debt is now over $40 trillion, a historic high that economists warn is bad news for the United States.