By Caitlin Ostroff and Gunjan Banerji

A slide in shares of technology giants weighed on the broader market Monday as investors grew wary of heightened regulation tied to the market's most enduring winners.

The S&P 500 declined 0.4%, after hitting a record on Friday. The tech-heavy Nasdaq dropped 0.9%. The Dow Jones Industrial Average shed 0.1%.

Tech heavyweights underperformed the broader market as they slashed access to some of President Trump's favorite megaphones after the storming of the Capitol by his supporters. The riot, planned and discussed on social media, is expected to spur Congressional efforts to regulate big tech. Facebook has indefinitely suspended President Trump, while Apple, Amazon.com and Alphabet's Google retracted support for the social-media app Parler.

Shares of Twitter fell 6.3% on concern that the social-media company may face a backlash from regulators or users after it banned Mr. Trump's personal account, citing the risk of further incitement of violence. Facebook shares lost 3.6% while Apple dropped 2.1%.

Stocks had rallied in recent days on bets that a Democrat-controlled Congress will increase government spending, bolstering an economic recovery that stagnated recently.

The monthly U.S. jobs report on Friday showed that the nation's labor-market recovery stalled in December, with seven months of job growth ending. Employers cut jobs last month as coronavirus cases continued to spread across the U.S., forcing restaurants and bars to close or scale down. Experts have warned this month of surges in new cases, hospitalizations and deaths after December's holiday gatherings and travel.

Market sentiment is dimming at the start of the new week as investors confront a number of risks. On the political front, House Democrats introduced an article of impeachment against President Trump. That is prompting concern that fresh rancor in Washington may diminish support for other important measures.

"Everything is a little bit bumpier than we expected it to be a week ago, " said Luca Paolini, chief strategist at Pictet Asset Management. "It feels like 2020 hasn't really ended. We are in the middle of a pandemic, we are still talking about U.S. politics even more than before. The underlying story is still pretty much the same."

To some investors, Monday's moves looked like a pause after a tremendous run for stocks to kick off the new year. The Dow on Friday notched its third record close of 2021.

The prospect of additional stimulus has pushed government-bond yields higher in recent days as investors bet on an uptick in economic growth and inflation. There also is a growing expectation that the government will issue more notes to pay for additional stimulus. Meanwhile, cyclical sectors like financials and energy have soared. These groups continued to edge higher in trading Monday despite the broader market's declines, a sign that some of those bets persisted.

"We're cautiously optimistic at this point," said Amy Kong, chief investment officer at Barrett Asset Management. "The markets have just been very strong."

On Monday, the yield on the 10-year Treasury note edged up to 1.112%, from 1.105% Friday. Yields rise when bond prices fall.

In corporate news, shares of NIO jumped about 10% after the electric-vehicle maker unveiled its fourth production model at its annual "NIO Day" Saturday. They were on track to close at a high. NIO has become wildly popular among investors, drawing chatter across social media and heavy trading volumes.

Eli Lilly shares jumped 11% after it said an experimental Alzheimer's drug helped patients in a small trial.

Overseas, the pan-continental Stoxx Europe 600 fell 0.7%.

China's Shanghai Composite declined 1.1% by the close of trading, while Hong Kong's Hang Seng edged 0.1% higher. Japan's markets were closed for a holiday.

Write to Caitlin Ostroff at caitlin.ostroff@wsj.com and Gunjan Banerji at Gunjan.Banerji@wsj.com

(END) Dow Jones Newswires

01-11-21 1604ET