Major U.S. equities indexes moved higher to kick off the week, with a shortened trading session on tap for Tuesday followed by a midweek day off in observance of Christmas.

The S&P 500 gained 0.7%. Strength in the tech sector helped lift the Nasdaq 1%, while the Dow staged an afternoon rally to eke out a daily gain of 0.2%.

Broadcom (AVGO) shares rose 5.5%, notching the top performance in the S&P 500, after UBS lifted its price target on the stock. Analysts said they boosted their forecasts for Broadcom's artificial intelligence revenue based on the chipmaker's disclosures about its addressable market along with an improving outlook for its custom compute and AI networking businesses.

Shares of Advanced Micro Devices (AMD) jumped 4.5% as analysts at Rosenblatt listed the semiconductor stock as one of their top picks for the first half of 2025. The investment research firm believes AMD is positioned for strength in the server and data center segment as it takes an increasing share of the central processing unit and graphic processing unit markets.

Other stocks in the semiconductor industry joined Monday's rally as the Biden administration announced a new investigation into legacy Chinese semiconductors used in U.S. products. Shares of microcontroller maker Microchip Technology (MCHP) and power circuit provider Monolithic Power Systems (MPWR) were more than 4% apiece, while chip industry giants Nvidia (NVDA), Intel (INTC), and Qualcomm (QCOM) also gained ground.

Carnival Corp. (CCL) shares sank 4%, falling the most of any S&P 500 stock. Monday's drop reversed gains posted at the end of last week after the cruise operator reported better-than-expected quarterly profits and provided an upbeat outlook for 2025 bookings. Analysts at Bernstein maintained their "market perform" rating on Carnival stock, pointing to a more favorable growth outlook for competing cruiser Royal Caribbean (RCL). Norwegian Cruise Line Holdings (NCLH) shares lost 2.9%.

Paramount Global (PARA) entered an agreement with the Federal Communications Commission (FCC) to pay fines for Emergency Alert System violations. A filing last week revealed a petition for the FCC to challenge Paramount's planned merger with production company Skydance Media, but reports have suggested that the relationship between Paramount boss Shari Redstone and President-elect Donald Trump could be beneficial as the incoming administration evaluates the deal. Shares of the entertainment giant lost 2.9%

Shares of cloud-based human resources software provider Workday (WDAY) declined 2.8% on Monday, the stock's first day of trading as a constituent of the S&P 500. The stock gained ground earlier in December following the announcement that it would join the benchmark index but has been volatile in recent weeks.

Shares of ResMed (RMD), a medical technology company focused on sleep apnea devices, lost 2.6% after the Food and Drug Administration approved Zepbound as a treatment for obstructive sleep apnea treatment in adults with obesity. Increased adoption of the blockbuster weight-loss drug from Eli Lilly (LLY) among sleep apnea patients could pressure sales of ResMed's continuous positive airway pressure, or CPAP, devices. Eli Lilly shares climbed 3.7%.