Stocks fell lower on Thursday as market participants grew more cautious over the high artificial intelligence stock valuations, which appear to be propping up the broader market.

The Dow Jones Industrial Average (DIA  ) cratered nearly 400 points on Thursday to settle at 46,912.30, while the broader market S&P 500 Index (SPY  ) lost about 1.1% to close at 6,720.32. The tech-heavy Nasdaq Composite (QQQ  ) also declined 1.9% to end the day at 23,053.99.

Chipmaker Qualcomm (QCOM  ) reported fiscal fourth-quarter results late Wednesday that topped Wall Street expectations and offered forward guidance that beat analyst estimates -- calling for first quarter revenue between $11.8 billion to $12.6 billion with adjusted earnings per share in range of $3.30 to $3.50 per share.

The company's shares ultimately fell on Thursday, however, after Qualcomm said it may lose future business with Apple (AAPL  ) for its wireless chips as the iPhone maker plans to use its own custom chips; the iPhone 16e and iPhone Air each use Apple's proprietary semiconductors.

Impacting outlooks on Thursday, layoff announcements for the month of October were almost triple September's rate, outplacement firm Challenger, Gray & Christmas reported. The month's total topped 153,000 and came in 175% higher than the same period a year ago.

"Like in 2003, a disruptive technology is changing the landscape," said Andy Challenger, chief revenue officer at the firm, in a statement. "At a time when job creation is at its lowest point in years, the optics of announcing layoffs in the fourth quarter are particularly unfavorable."

The data offers only a glimpse at the overall picture of the U.S. labor market in response to the emerging artificial intelligence sector, as most economic reports have stalled due to the ongoing federal government shutdown. On Wednesday, private payrolls processing firm ADP reported that U.S. employers added 42,000 positions last month, with information services posting a notable decline of 17,000 jobs.

Elsewhere, President Donald Trump announced deals with Eli Lilly (LLY  ) and Novo Nordisk (NVO  ) on Thursday to lower the prices of their injectable and oral obesity drugs for Medicare and Medicaid users in 2026. The treatments will be offered directly to consumers at a discount on the Trump administration's upcoming TrumpRx.gov, launching in January.

"This is the biggest drug in our country, and that's why this is the most important of all the [most favored nation] announcements we've made," Health and Human Services Secretary Robert F. Kennedy Jr. said during a press briefing on Thursday. "This is going to have the biggest impact on the American people. All Americans, even those who are not on Medicaid, Medicare, are going to be able to get the same price for their drugs, for their GLP-1s."

Looking ahead, investors will react to earnings reports from companies including Airbnb (ABNB  ), Take-Two Interactive Software (TTWO  ), Block (XYZ  ), and Constellation Energy (CEG  ) on Friday. The University of Michigan will also release its preliminary consumer sentiment reading for November in the morning.