US stock markets turned lower on Monday as investors awaited key data that could play a role in Federal Reserve deliberations ahead of an expected cut to interest rates next week.

Wall Street's three main indices finished lower, with the S&P 500 losing 0.5 percent after spending the entire session in the red.

Bitcoin extended its decline, dropping more than five percent to under US$85,500 amid weaker risk appetite.

The cryptocurrency remains well below its record high above US$126,200 struck in early October.

"Bitcoin tends to be a leading indicator for overall risk sentiment right now, and its slide does not bode well for stocks at the start of this month," said Kathleen Brooks, research director at trading group XTB.

Coinbase, which ended down 4.8 percent, and US-listed shares of Bitfarms, off 5.7 percent, were among the crypto stocks that showed significant weakness

Expectations that the Federal Reserve would continue easing monetary policy into the new year have recently helped equities mitigate lingering concerns about an artificial intelligence-fuelled bubble.

Markets see a nearly 90-percent chance of a third successive US rate cut on December 10, with traders closely watching this week's American data on private jobs creation, services activity and personal consumption expenditure – the Fed's preferred gauge of inflation.

Bets on a rate cut surged in late November after several Fed policymakers expressed greater concern over a weakening labour market than stubbornly high inflation.

A survey released on Monday of manufacturers by the Institute for Supply Management added to this sentiment. The reading fell to 48.2 from 48.7, the ninth straight month of contraction. Clothing, fabricated metal productions and transportation equipment manufacturers were among those reporting contraction.

Oil prices climbed more than one percent after Opec+ confirmed it would not hike output in the first three months of 2026, citing lower seasonal demand.

While the move was anticipated, "it was enough to catalyse a move which drove out the weaker short players," said Trade Nation analyst David Morrison.

Traders who bet that oil prices might have dropped if Opec+ prevaricated had to cover their positions, thus helping push up prices further.

The Opec+ decision comes amid uncertainty over the outlook for crude as traders look for indications of progress in Ukraine peace talks, which could lead to the return of Russian crude to markets.

Shares in plane manufacturer Airbus fell by more than 10 percent at one point, after reports of a new problem affecting metal fuselage panels, although they later cut losses after the company said the problem had been contained.

The S&P 500 fell 0.5 percent, to 6,812, breaking a five-day winning streak. The Dow Jones Industrial Average fell 0.9 percent, to 47,289, and the Nasdaq fell 0.4 percent to 23,275. (AFP/ Reuters)