Stocks were mixed Monday following positive news from Chinese startup DeepSeek's reasoning AI model, sparking a sell-off of major technology stocks. The broader market S&P 500 Index fell nearly 1.5% and the tech-heavy Nasdaq Composite lost more than 3% Monday, while the Dow Jones Industrial Average rose nearly 300 points as market participants rotated out of growth stocks.

Here's how the market settled on Monday:

S&P 500 Index (SPY  ): -1.46% or -88.96 points to 6,012.28

Dow Jones Industrial Average (DIA  ): +0.65% or +289.33 points to 44,713.58

Nasdaq Composite Index (QQQ  ): -3.07% or -612.47 points to 19,341.83

Shares of AI-related stocks including Nvidia (NVDA  ), Microsoft (MSFT  ), Amazon (AMZN  ), Broadcom (AVGO  ), Advanced Micro Devices (AMD  ) and Arm Holdings (ARM  ) each plugged deeper into the red on Monday as DeepSeek launched a free, open-source large language model last week that has reported outperformed OpenAI's latest model in multiple third-party tests. The Chinese tech startup also claims that its first large language model, released last month, costed less than $6 million to design.

"It's a good example of selling first and asking questions later, and investors sort of feeling that valuations are a bit stretched for technology in general and for semiconductors in particular," said Sam Stovall, chief investment strategist at CFRA Research. "We're going to have volatility, especially when we're dealing with a richly valued market and exogenous events."

DeepSeek on Monday overtook OpenAI's ChatGPT on the Apple (AAPL  ) App Store as the most downloaded free app in the United States. The company said it would temporarily limit user registrations on Monday "due to large-scale malicious attacks," on its services.

UBS Strategist Sundeep Gantori wrote in a Monday note to clients to expect some more tech volatility in 2025, as the AI industry has fueled the bull market rally for the last two years.

"Tech sector volatility could pick up in 2025. But we also expect robust capital spending and further progress on AI monetization, with strong earnings supporting our preferred stocks," Gantori wrote. "We view the U.S. IT sector as Attractive due to its promising fundamentals, and recommend investors to use any near-term volatility to build up sufficient exposure to quality AI stocks."

On the Earnings Front:

AT&T (T  ) reported strong wireless subscriber growth in its fourth quarter, benefitting from its discounted premium plans that bundle 5G mobile and high-speed fiber data services. The telecom added 482,000 net monthly wireless phone subscribers, topping expectations, while its fiber business added 307,000 new customers. Looking ahead, AT&T expects annual adjusted profit between $1.97 and $2.07 per share, excluding the contribution from its 70% stake in DirecTV.

In the News:

Apple released its latest software update for iPhones, iPads and Macs on Monday that turns on its AI serves, Apple Intelligence, on supported devices by default. The updates -- iOS 18.3, iPadOS 18.3 and macOS Sequoia 15.3, also notably disables AI summaries for news and entertainment apps, which have been criticized for displaying inaccurate facts.

The move is the tech giant's latest step to completely rollout the service, as previous releases requiring users to turn on Apple Intelligence in their Settings app and download AI models from the internet. Now, all users on supported devices will be able to rewrite text, generate image and summarize message thread and emails by default -- having to choose to turn the service off in their Settings app.

For Tuesday:

Market participants will turn their attention towards earnings reports from companies including Boeing (BA  ), Royal Caribbean Cruises (RCL  ), General Motors (GM  ), Kimberly-Clark (KMB  ) and Lockheed Martin (LMT  ) on Tuesday. The Federal Reserve all kicks off its two-day policy setting meeting on Tuesday, its first of the year.