Major U.S. equities indexes were mixed as December trading began, with many households eying Cyber Monday deals as U.S. retailers wrapped up a huge shopping weekend.

Meanwhile, investors will examine several economic data points this week, culminating in Friday's release of the November jobs report.

The S&P 500 added 0.2% on Monday, reaching its highest-ever close for the second straight session. The Nasdaq also printed a closing high, jumping 1% on a strong day for the technology and communication sectors. The Dow slipped 0.3%.

Super Micro Computer (SMCI) shares surged 28.7%, leading the S&P 500 higher on Monday. The volatile stock's latest jump came after Supermicro said an independent review committee had found no evidence of accounting misconduct or fraud. The server maker also announced changes to shore up its governance structure, including a new chief financial officer, chief compliance officer, and general counsel.

Semiconductor equipment stocks extended gains posted late last week following reports that proposed restrictions on exports to China could be less stringent than previously anticipated. Lam Research (LRCX) shares added 6.3% on Monday, while Applied Materials (AMAT) stock was up 4.9%. 

Shares of cruise operators notched gains following positive commentary on industry booking and pricing trends from analysts at Truist. Norwegian Cruise Line Holdings (NCLH) shares sailed 5.4% higher after Truist boosted its price target on the stock, indicating that the company appears to be on track to meet the implied sales guidance provided at its recent investor day. Shares of Carnival (CCL) and Royal Caribbean (RCL) also advanced.

Shares of Texas Pacific Land (TPL), which owns significant acreage in the oil-rich Permian Basin, sank 6.1%, losing the most of any S&P 500 stock. The stock enjoyed a boost as it joined the S&P 500 in late November but has reversed those gains heading into December.

PG&E shares (PCG) dropped 5% after the California-based electric utility holding company said it would raise $2.4 billion through public offerings of new common and mandatory convertible preferred stock. PG&E plans to use the proceeds from the offering for general corporate purposes, which could include funding its five-year capital investment plan.

Natural gas prices moved lower as forecasts for milder winter weather raised questions about the key heating fuel demand. U.S. natural gas inventory levels heading into the winter are reportedly at their highest level since 2016. The price decline pressured shares of companies in the natural gas industry. Shares of pipeline operators Targa Resources (TRGP) and Oneok (OKE) fell 4.6% and 2.8%, respectively.