US benchmark stock indexes were mixed as the so-called Magnificent 7 group of stocks declined after midday on Monday, helping send the S&P 500 and the Nasdaq Composite lower.

The tech-heavy Nasdaq dropped 0.8% to 19,016.9, and the S&P 500 fell 0.1% to 5,819.5. Both indexes were off their session lows. The Dow Jones Industrial Average rose 0.6% to 42,194.5, increasing gains from earlier in the session. Technology and utilities led the steepest decliners while energy and materials were among the top gainers intraday.

Most US Treasury yields traded mixed. The 10-year stood little changed at 4.78% after touching a new 52-week high earlier in the session. The 10-year ended higher last week following Friday's blockbuster nonfarm payrolls report that beat market expectations, increasing the probability of the Federal Reserve remaining on a policy pause throughout this year as per data compiled by the FedWatch Tool.

Nvidia (NVDA), Apple (AAPL), Meta Platforms (META), Tesla (TSLA), and Alphabet (GOOG, GOOGL) were in the steepest 10 decliners intraday among mega-caps, which are firms with a market capitalization of more than $200 billion. Microsoft (MSFT) and Amazon.com (AMZN), the two remaining Magnificent 7 companies, were in the 20 worst performers intraday. As of late 2024, these seven companies reportedly accounted for about 31% of the S&P 500.

The Magnificent 7 are declining ahead of December's producer price index release on Tuesday and the consumer price index on Wednesday amid concern a hot inflation print would push Treasury yields even higher. Friday's University of Michigan consumer expectations survey showed the five-year inflation outlook accelerated to 3.3% from 3% a month ago.

The upcoming inflation data may reinforce the sentiment that the Federal Open Market Committee will likely remain on hold for "some time" if the December CPI consensus estimates come in as expected, a Scotiabank note said late Friday.

"We see US equity gains cooling from their highs this year but staying strong, while US Treasury yields climb," BlackRock said in a note Monday. "We stay overweight US stocks and underweight long-term Treasuries, yet we're watching triggers to change our views."

Goldman Sachs pushed back its rate cuts this year to two, in June and December, from three set out previously, it said in a note Monday. It expects one rate reduction next year in June to a terminal rate of 3.5% to 3.75%. "It is hard to have conviction in the exact timing of cuts because it is hard to know how the FOMC will navigate likely tariff increases."

Meanwhile, West Texas Intermediate crude oil futures soared 3.3% to $79.03 a barrel, its highest level since mid-August on an intraday basis, after the US announced new sanctions on Russia.

The sanctions include producers Gazprom Neft and Surgutneftegas, along with more than 180 vessels that have shipped Russian oil, Reuters said in a news report Monday. The exports are expected to be significantly affected by the sanctions, and China and India will likely source more crude from the Middle East, Africa, and the Americas, boosting prices and shipping costs, Reuters reported, citing traders and analysts.

In company news, Johnson & Johnson (JNJ) on Monday agreed to acquire Intra-Cellular Therapies (ITCI) for about $14.6 billion in cash to strengthen its neuroscience portfolio. Intra-Cellular jumped more than 34% and Johnson & Johnson added 1.4%.

Moderna (MRNA) sank 19%, the worst performer on the S&P 500, after the company said it now expects 2025 revenue to be between $1.5 billion and $2.5 billion, down from the previous range of $2.5 billion to $3.5 billion.

Gold futures dropped 1.3% to $2,680.22 an ounce, and their silver counterpart slumped 3.2% to $30.32 per ounce.