By Echo Wang

(Reuters) -Wall Street's main indexes closed lower on Monday, driven by a drop 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 2.5% after China's market regulator launched an investigation into the chipmaker over suspected violation of antimonopoly law, dragging the information technology sector down 0.45%.

Advanced Micro Devices slipped 5.7% after BofA Global Research downgraded its rating on the stock, weighing on the Philadelphia Semiconductor Index, which slipped 0.87%.

"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 Dow Jones Industrial Average fell 240.59 points, or 0.54%, to 44,401.93, the S&P 500 lost 37.42 points, or 0.61%, to 6,052.85 and the Nasdaq Composite lost 123.08 points, or 0.62%, to 19,736.69.

Nine out of 11 S&P 500 sectors lost ground, led by declines in financial stocks.

Comcast slid 9.5% after forecasting a loss of more than 100,000 broadband subscribers in the fourth quarter, denting the communication services sector by 1.3%.

Shares of Hershey surged 10.9% following a media report that Cadbury parent Mondelez was exploring an acquisition of the chocolate maker. Mondelez shares fell 2.3%.

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.

Bets of a 25-basis-point rate cut at the upcoming meeting shot up to more than 85% after data on Friday showed a rise in the unemployment rate to 4.2% in November, indicating an easing labor market.

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.

On Monday, Workday rose 5.1% after S&P Dow Jones Indices said last week the company would be added to the S&P 500 index.

Interpublic Group climbed 3.6% following a report that marketing giant Omnicom was in advanced talks to acquire the advertising company. Omnicom shares fell 10.3%.

U.S. 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.