The S&P 500 closed at an all-time high on Monday — again.

For the second consecutive trading session, the index soared past its previous record as markets charged higher heading into the final week of 2021. All three major U.S. indexes gained in a promising sign for stock market bulls that a Santa Claus Rally is well underway.

At close, the S&P was up 1.38% to 4,791.19, while the Dow saw a 350-point jump to 36,302.38. The Nasdaq Composite also gained 1.39%, closing at 15,871.26.

The S&P's move marked its 69th record close of the year after the index hit an intraday high in morning trading, up even as COVID-19 cases rise.

The year-end Santa Claus Rally — one in which stocks climb higher in the final five trading sessions of a year, plus the first two trading days of the new year — is building momentum. For reasons unclear, over the past 92 years, the S&P 500 gained 77% of the time during the year-end rally period, according to data from Sundial Capital Research. The average gain in this seven-day trading period tallied 2.66%.

The market will head into 2022 with several key considerations to weigh but with its biggest focus on the course of the pandemic and rising inflationary pressures as well as on measures the Federal Reserve could take in response.

“Inflation and Omicron are the two most important catalysts for the stock market right now,” APAC CEO at Qraft Technologies Francis Oh told Yahoo Finance. “I think that those catalysts are priced in through the market volatility… still I think the market will cautiously move off.”

Merck (MRK) received authorization last week from the U.S. Food and Drug Administration for its at-home COVID-19 drug, just one day after Pfizer (PFE) was also approved for use of its own treatment.

The pill developed by Merck in conjunction with Ridgeback Biotherapeutics, called molnupiravir, was shown to reduce hospitalizations and deaths by around 30% in clinical trial data. Pfizer's pill was reported to be 90% effective at preventing hospitalizations and deaths in high-risk patients.

“One of the ways pandemics end is significant mutation of the virus. It looks like Omicron may be our friend in that regard, significant mutations different enough from the parent that it doesn’t make people as sick,” True Health Initiative President Dr. David Katz told Yahoo Finance Live.

Investors processed a trove of economic releases ahead of the holiday weekend.

The Labor Department reported that initial jobless claims totaled 205,000, sustaining a downward trend from the highs of their pandemic peak and reflecting labor market tightness brought on by a demand for workers heading into the new year. The latest print brings the four-week moving average for new claims to its lowest in 52 years, ticking up by 2,750 week-over-week to reach 206,250.

Meanwhile, U.S. consumer prices accelerated at the fastest pace in nearly four decades as shoppers confront rising inflation levels ahead of the holidays.

“Workers have a lot of power, and that’s likely to result in continued wage gains,” Girard chief investment officer Timothy Chubb told Yahoo Finance. “What worries us from an inflation standpoint is, at what point do we potentially see some of those inflation risks sort of hand the baton to the labor market?”

Meanwhile, November sales of new U.S. homes jumped 12.4% to a seven-month high of 744,000, buoyed by low mortgage rates and higher demand in the housing industry.

U.S. durable goods orders rose by 2.5% in November, up from the prior month, boosted by a sharp rise in aircraft orders.

“We’ve been saying that this is definitely a buy the dip sort of market because we expect more earnings upgrades to come,” Anik Sen, PineBridge Investments global head of equities told Yahoo Finance Live. “We think that the real debate should be about the length and strength of the economic cycle ahead.”

4:15 p.m. ET: Apple tip-toes around $3 trillion valuation

Shares of Apple Inc. (AAPL) closed 2.3% higher at $180.33 a piece, bringing the stock to a new record close.

The gains added more than $66 billion to the company's market capitalization, bringing it up to $2.96 trillion, according to Bloomberg data.

Apple's climb comes on a positive day for the broader tech sector and strong day for markets overall.

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4:00 p.m. ET: S&P sees another record closing high

Here's how markets closed out the trading session ET:

• S&P 500 (^GSPC): +65.55 (+1.39%) to 4,791.34

• Dow (^DJI): +352.21 (+0.98%) to 36,302.77

• Nasdaq (^IXIC): +217.89 (+1.39%) to 15,871.26

• Crude (CL=F): +$1.90 (+2.57%) to $75.69 a barrel

• Gold (GC=F): +$0.90 (+0.05%) to $1,812.60 per ounce

• 10-year Treasury (^TNX): -1.2 bps to yield 1.4810%

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2:28 p.m. ET: Fauci says U.S. should implement vaccine mandate for domestic travel

The nation's top infectious disease expert Dr. Anthony Fauci said the United States should "seriously" consider requiring COVID-19 vaccines for domestic flights during an appearance Monday morning on MSNBC’s “Morning Joe."

“When you make vaccination a requirement, that’s another incentive to get more people vaccinated,” he said. “If you want to do that with domestic flights, I think that’s something that seriously should be considered.”

The statement comes as the recent Omicron-driven wave spurs flight cancellations across the country, driven mostly by staff shortages caused by the virus. More than 1,000 U.S. flights were canceled Monday as of 1 p.m. ET, according to Bloomberg.

Airline stocks remained in the red during midday trading, with American Airlines (AAL) down 0.58% to $18.16 per share, United Airlines (UAL) falling 0.89% to $44.47 a piece, and Delta Air Lines (DAL) ticking 0.98% down to trade at $38.92 per stock.

“If the stocks are down, now is the time to buy,” DLB Financial Services CEO Debbie Boyd told Yahoo Finance Live as she discussed airline companies. “Think of those stocks being down as on sale.”

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12:17 p.m. ET: Markets edge higher during intraday trading

Here's how stocks were trading in the midday session ET:

• S&P 500 (^GSPC): +48.18 (+1.02%) to 4,773.97

• Dow (^DJI): +230.93 (+0.64%) to 36,181.49

• Nasdaq (^IXIC): +174.28 (+1.11%) to 15,827.65

• Crude (CL=F): +$1.99 (+2.70%) to $75.78 a barrel

• Gold (GC=F): -$1.20 (-0.07%) to $1,810.50 per ounce

• 10-year Treasury (^TNX): -1.2 bps to yield 1.4810%

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11:41 a.m. ET: Tesla climbs towards biggest four-day gain since March

Shares of Tesla jumped 3.52% to $1,104.55 a piece, leading most of its peers in the electric vehicle space and approaching the company's best four-day streak of gains since March.

Among other stocks in the sector, Lucid Group (LCID) gained 1.30% in intraday trading to $38.13 per share, Nikola (NKLA) was flat, trading at about $11.09 a piece, and Canoo (GOEV) was down 2.64% to $8.28 per share. Rivian (RVN) was up 5.73% to $102.39 per share.

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9:53 a.m. ET: Airline stocks descend following weekend of cancellations

U.S. travel stocks slumped in early trading after major airlines reported hundreds of cancellations and delays amid staffing shortages caused by an uptick of COVID-19 cases among crews and personnel.

More than 2,800 flights were disrupted over the Christmas weekend, caused by the latest coronavirus wave and inclement weather from a winter storm in the northwestern part of the country.

American Airlines (AAL) dropped -2.70% to $17.77 per share at market open. United Airlines (UAL) and Delta Air Lines (DAL) each tumbled 2% to $44.01 and $38.47 per share, respectively.

Cruise ship operators also took a hit, with Carnival Corp. (CCL) sinking 3.5% to $20.45 per share, Royal Caribbean Cruises (RCL) down 3.1% to $77.07 per share and Norwegian Cruise Line Holdings (NCLH) trading down 4.14% to $21.78 per share.

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9:30 a.m. ET: Markets open higher heading into final trading week of 2021

Here were the main moves at the start of the trading session ET:

• S&P 500 (^GSPC): +11.51 (+0.24%) to 4,737.30

• Dow (^DJI): +61.77 (+0.17%) to 36,012.33

• Nasdaq (^IXIC): +131.47 (+0.85%) to 15,653.37

• Crude (CL=F): -$0.25 (-0.34%) to $73.54 a barrel

• Gold (GC=F): -$1.50 (-0.08%) to $1,810.20 per ounce

• 10-year Treasury (^TNX): -1.2 bps to yield 1.4810%

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7:10 a.m. Monday ET: Futures inch higher after Christmas weekend

• S&P 500 futures (ES=F): +8.00 (+0.17%), to 4,723.75

• Dow futures (YM=F): +13.00 points (+0.04%), to 35,845.00

• Nasdaq futures (NQ=F): +39.50 points (+0.24%) to 16,338.50

• Crude (CL=F): -$1.07 (-1.45%) to $72.72 a barrel

• Gold (GC=F): -$4.80 (-0.26%) to $1,806.90 per ounce

• 10-year Treasury (^TNX): -0.09 bps to yield -0.07%

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Correction: The year-end Santa Claus Rally is when stocks climb higher in the final five trading sessions of a year, plus the first two trading days of the new year. The number of days was misstated in an earlier version of this article.

Alexandra Semenova is a reporter for Yahoo Finance. Follow her on Twitter @alexandraandnyc

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