US stocks on Monday retreated from records set last week as political uncertainty, including efforts to remove President Donald Trump from power, has finally shaken investors.

While they were unmoved by the violent invasion of the US Capitol by Trump supporters last week, the three major indices all closed lower in the first session of the week.

The benchmark Dow Jones Industrial Index was down 0.3 percent to end at 31,008.69.

The broad-based S&P 500 fell 0.7 percent to 3,799.61, while the tech-rich Nasdaq Composite Index dropped 1.2 percent to finish at 13,036.43.

Art Hogan, chief market strategist at National Securities, said investors can only ignore bad news for so long.

The bad news included data showing spiking Covid-19 cases led to the first job losses since April.

The New York Stock Exchange (NYSE) has seen retreats as Covid-19 cases spike and markets process the prospect of outgoing President Donald Trump facing impeachment for last week's attack on the Capitol by his followers
The New York Stock Exchange (NYSE) has seen retreats as Covid-19 cases spike and markets process the prospect of outgoing President Donald Trump facing impeachment for last week's attack on the Capitol by his followers GETTY IMAGES NORTH AMERICA / SPENCER PLATT

The market "was able to look through the insurrection, the attack on the Capitol (and) lousy job numbers last week," he told AFP.

"But you get to a point where you have to stop pricing in the future and look at the here and now."

Amid concerns about rising coronavirus infections and reports about stumbles in the vaccine rollout, traders are monitoring the intensifying debate among Democrats over how to hold Trump to account for inciting a mob to attack the US Capitol last week.

But a lengthy impeachment process could distract from President-elect Joe Biden's economic aid plans, which he is due to unveil later this week.

Meanwhile, tech companies that have banned Trump's account and Parler, the platform favored by many on the extreme right, were hit in the session: Twitter lost 6.4 percent and Facebook fell 4.0 percent, while Apple and Amazon each dropped more than 2 percent.