The main US indices finished lower on Monday, fueled by a decline in AI leader Nvidia that weighed on tech stocks, as investors looked ahead to a crucial inflation report set for later this week.

Nvidia fell after China's market regulator launched an investigation into the chipmaker over suspected violation of antimonopoly law, dragging down the information technology sector.

Advanced Micro Devices slipped after BofA Global Research downgraded its rating on the stock, weighing on the Philadelphia Semiconductor Index.

"The market was taken a bit by surprise regarding China's investigating (Nvidia) as a possible antimonopoly-law violation. So that's one thing that's putting a little damper on the market," said Sam Stovall, chief investment strategist at CFRA Research in New York.

The S&P 500 lost 37.92 points, or 0.6 percent, to end at 6,052.35, and the Nasdaq Composite lost 123.08 points, or 0.6 percent, to 19,736.69. The Dow Jones Industrial Average fell 240.59 points, or 0.5 percent, to 44,401.93.

Comcast declined after forecasting a loss of more than 100,000 broadband subscribers in the fourth quarter, denting the communication services sector.

Shares of Hershey soared following a report that Cadbury parent Mondelez was exploring an acquisition of the chocolate maker. Mondelez shares fell.

Investors are anticipating the consumer price index (CPI) data set for release on Wednesday, along with the producer price index (PPI) on Thursday, ahead of the Federal Reserve's meeting on Dec. 17-18.

Several Fed officials, including Chair Jerome Powell, emphasized caution regarding the central bank's approach to easing monetary policy due to the economy's resilience.

Wall Street's main indexes started December on a positive note, with the benchmark S&P 500 and the tech-heavy Nasdaq both gaining in their first week, while the blue-chip Dow ended the week slightly lower.

US stocks soared in November after Donald Trump won the presidential election and his party secured control of both houses of Congress, raising expectations for a more business-friendly policy agenda. (Reuters)