The S&P 500 lost ground at the end of a whipsaw session on Tuesday as concerns over a new variant of the coronavirus and disappointing economic data stole the thunder from Washington's passage of a long-awaited pandemic relief bill.
The Dow also closed lower, while Apple Inc helped fuel the tech-heavy Nasdaq's advance.
"Today the market is catching its breath," said Ryan Detrick, senior market strategist at LPL Financial in Charlotte, North Carolina. "It's digesting the two big pieces of news we've gotten in the last 24 hours, the stimulus and the new Covid-19 strain."
Still, this is typically a seasonally bullish time of year, Detrick added, saying "the market doesn't care about the past or present. The market only cares about the future."
Apple was an outlier amid a broad sell-off, its stock jumping on news of the company's plans to roll out an electric passenger vehicle by 2024.
Overnight, Congress passed a pandemic relief package worth $892 billion after months of a partisan tug-of-war, aimed at propping up an economic recovery faltering under the weight of restrictions aimed at containing a coronavirus resurgence.
That resurgence continues to swell, infecting 214,000 Americans every day, prompting mandatory shutdowns and pushing hospitals to capacity.
A fast-spreading new variant of the virus discovered in Britain has brought movement in and out of the UK to a halt and sent vaccine makers Pfizer Inc and Moderna Inc scrambling to ensure their drugs were effective against it.
Fears of the coronavirus and optimism about an eventual economic recovery made for extreme volatility on Wall Street in 2020, with the S&P 500 logging daily gains or losses of 2% or more over 40 times in the year so far, the most in over a decade.
"This will be the first year in history when stocks were off 30% for the year at one point and finished in the green," Detrick said. "It's truly an amazing round-trip and we've never seen anything like it."
On the economic front, consumer confidence unexpectedly dropped while sales of pre-owned U.S. homes posted their first decline in six months.
Unofficially, the Dow Jones Industrial Average fell 202.12 points, or 0.67%, to 30,014.33, the S&P 500 lost 7.67 points, or 0.21%, to 3,687.25 and the Nasdaq Composite added 65.40 points, or 0.51%, to 12,807.92.
Tesla Inc closed lower, extending its slide on its second day as a S&P 500 constituent.
Peloton Interactive Inc jumped as brokers hiked their price targets on the stock on the heels of the company's announcement that it would buy peer Precor in a deal worth $420 million.
Amgen Inc slid after disappointing results from a late-stage study of an asthma drug developed in a partnership with British drugmaker AstraZeneca Plc.