By Joe Wallace and Gunjan Banerji

The S&P 500 drifted lower Friday, putting Wall Street on track to end a choppy week with muted losses.

The broad stock-market gauge slipped 0.3% in recent trading. The Dow Jones Industrial Average fell 0.5%. The tech-heavy Nasdaq Composite rose about 0.1%.

A winning stretch for the stock market has stagnated recently, after enthusiasm about the development of effective coronavirus vaccines propelled the Dow industrials to a record at the start of the week. Surging coronavirus infections, signs that the economy has lost momentum, and the U.S. Treasury's decision to allow several emergency Federal Reserve programs to expire have deflated some of the optimism.

Some investors said the recent moves mark a healthy pause after a vigorous rally since the presidential election.

"You're got just this spike up with so many stocks," said Mark Stoeckle, chief executive of Adams Funds. "I do think we need a breather here."

The S&P 500 and Dow are on track to end the week lower 0.4% and 0.5%, respectively. The Nasdaq is poised for a gain of 0.7%.

A number of factors have raised concerns among investors in recent days. Treasury Secretary Steven Mnuchin said Thursday that several novel programs that have backed corporate credit and municipal-borrowing markets would end Dec. 31. Mr. Mnuchin asked the Fed to return more than $70 billion in funds that had already been transferred to the central bank to cover loan losses.

The decision raises uncertainty about the degree of support that will be in place for the economy if states impose further restrictions to quell the wave of infections.

Every indicator of the virus's spread across the U.S. continued to accelerate. The country logged its highest-ever number of newly reported Covid-19 infections in a day Thursday and reported record-high hospitalizations for the 10th day in a row. California Gov. Gavin Newsom issued a new stay-at-home order that will require the most of residents to stay at home and businesses to close between 10 p.m. and 5 a.m.

"We're looking at short-term negatives," said Paul Jackson, head of asset allocation research at Invesco. "The markets are busy trying to balance that with the longer-term good news that is coming from vaccines."

The lack of agreement in Congress on a new round of aid for the economy has weighed on investor sentiment lately.

"The U.S. economy still needs stimulus to get over the hump at the moment," said Brian O'Reilly, head of market strategy at Mediolanum International Funds. Still, Mediolanum is positioning its funds for a bounceback next year in shares of industries, such as financial services and materials, that have suffered during the pandemic.

In corporate news, shares of Pfizer rose 1.5% after the pharmaceutical giant said it plans to ask U.S. health regulators on Friday to permit use of its Covid-19 vaccine. It will be up to the U.S. Food and Drug Administration to decide whether the two-shot vaccine works safely enough to roll out to millions of people.

Gilead Sciences fell 0.8% after the World Health Organization recommended against the use of antiviral drug remdesivir for Covid-19.

Tesla shares are on track to soar 20% this week after S&P Dow Jones Indices said the stock would be joining the S&P 500 index.

In bonds, the yield on 10-year U.S. Treasury notes slipped to 0.831%, from 0.854% Thursday.

Overseas, basic-resources, retail and oil-and-gas stocks led European markets higher. The pan-continental Stoxx Europe 600 edged up 0.5%.

The Shanghai Composite Index gained 0.4%, and Japan's Nikkei 225 ticked down 0.4%.

Write to Joe Wallace at Joe.Wallace@wsj.com and Gunjan Banerji at Gunjan.Banerji@wsj.com

(END) Dow Jones Newswires

11-20-20 1530ET