While all three major stock indexes closed in the red, a gain Microsoft Corp shares helped the mitigate the tech-heavy Nasdaq's loss.

Johnson & Johnson announced on Monday it was pausing clinical trials of a COVID-19 vaccine candidate due to an unexplained illness in a study participant. The delay weighed on the company's shares, even after its beat-and-raise earnings report. Its shares lost 2.3%.

Late in the session, rival Eli Lilly & Co said it was also halting its coronavirus antibody trial because of safety concerns, sending its shares down 2.9%.

"We have this recent spike in coronavirus cases coinciding with big drug companies halting vaccine trials," said Robert Pavlik, chief investment strategist at SlateStone Wealth LLC in New York. "That's making the market nervous and in response, you're seeing the lockdown stocks moving higher."

Hopes for the passage of a new coronavirus relief package faded as U.S. House Speaker Nancy Pelosi rejected the $1.8 trillion coronavirus relief proposal from the White House, saying it "falls significantly short of what this pandemic and deep recession demand."

Senate Majority Leader Mitch McConnell said the Republican-led Senate would vote on a targeted pared-down stimulus package on Monday.

"(Washington is) playing with the market's emotions and individuals' financial futures," SlateStone Wealth's Pavlik added. "As this continues, the market is looking past what they're saying because it truly believes stimulus will come some time after the election."

Although JPMorgan handily beat consensus profit estimates, gaining from a boom in its trading business, its peer Citigroup, while also beating expectations, was slammed by low interest rates and a slowdown in loan demand. Their shares dropped 1.6% and 4.8%, respectively.

The broader S&P Banking index lost 2.7%

Apple Inc unveiled the latest incarnation of its flagship gadget, the iPhone 12 with 5G connectivity. Its shares were down 2.7%.

The Dow Jones Industrial Average fell 157.71 points, or 0.55%, to 28,679.81, the S&P 500 lost 22.29 points, or 0.63%, to 3,511.93 and the Nasdaq Composite dropped 12.36 points, or 0.1%, to 11,863.90.

Third-quarter reporting season has left the starting gate, and analysts now see S&P 500 earnings, in aggregate, falling by 19.6% year-on-year, according to Refinitiv.

Other earnings on tap this week include Bank of America Corp, Goldman Sachs Group Inc, Wells Fargo & Co, UnitedHealth Group and United Airlines Holdings Inc expected on Wednesday, with Morgan Stanley and Honeywell International Inc due on Thursday.

Shares of Delta Air Lines Inc dropped 2.7% after the commercial carrier reported a 76% plunge in quarterly revenue and announced it has delayed a targeted halt to its cash bleed.

Planemaker Boeing Co reported order cancellations for its grounded 737 MAX aircraft and said deliveries were less than half the number as the same month a year ago. Its stock, was down 3.1% was the heaviest drag on the Dow.

Declining issues outnumbered advancing ones on the NYSE by a 2.00-to-1 ratio; on Nasdaq, a 1.50-to-1 ratio favored decliners.

The S&P 500 posted 39 new 52-week highs and one new low; the Nasdaq Composite recorded 123 new highs and 14 new lows.

Volume on U.S. exchanges was 8.50 billion shares, compared with the 9.72 billion average over the last 20 trading days.

(Reporting by Stephen Culp; Editing by Marguerita Choy)

By Stephen Culp