By Sinéad Carew

NEW YORK (Reuters) - The S&P 500 and the Dow rallied sharply but closed shy of their records on Monday as investors bet that a full economic reopening was finally in sight following the first positive data from a late-stage COVID-19 vaccine trial.

U.S. crude oil rose more than 8% and pushed up energy stocks while safe-haven U.S. Treasuries sold off after U.S. drugmaker Pfizer and its German partner BioNTech said a large-scale trial of their vaccine showed it was more than 90% effective in preventing COVID-19.

Investors said they were also reassured by Saturday's news that Joe Biden had garnered enough votes to win the U.S. presidential election as they had priced in this news last week.

"Election uncertainty is fading into the rearview mirror. Now we have this boost of investor enthusiasm after the vaccine news," said to Michael Antonelli, market strategist at Baird in Milwaukee. "All the types of companies that would benefit from us returning to a pre-COVID world are the big winners today."

Sectors such as energy, travel and financials which were among the hardest hit by lockdowns aimed at curbing the virus were some of the biggest percentage gainers on Monday.

While their vaccine study is still ongoing and requires approval, Pfizer and BioNTech said they had found no serious safety concerns so far and expected to seek U.S. emergency use authorization later this month.

"It's not that we're out of the woods with COVID. It's that the vaccine starts to remove the worst case scenario that we surge out of control and go back into a national lockdown," said Antonelli. "The market's looking into the future, to the first and second quarter of next year."

However the S&P pared some gains late in the session. U.S. Senate Majority Leader Mitch McConnell on Monday said President Donald Trump was completely within his rights to look into "irregularities" from last week's election.

Paul Nolte, portfolio manager at Kingsview Investment Management in Chicago, pinned the late session fading on "profit-taking" after the morning rally.

The Dow Jones Industrial Average rose 834.57 points, or 2.95%, to 29,157.97 in its biggest one-day percentage gain since June 5. The S&P 500 rose 41.06 points, or 1.17%, to 3,550.5 and the Nasdaq Composite dropped 181.45 points, or 1.53%, to 11,713.78.

With a 14% advance the S&P energy index led gainers among the S&P 500's 11 major sectors and registered its biggest daily percentage gain since March as investors bet demand would climb again when people become more comfortable with the idea of traveling as the health crisis subsides.

Also, bank shares, often seen as a proxy for the broader economy, soared 13% in their biggest one-day advance since late March to hit their highest level since June.

The companies hit hardest by months of travel bans and lockdowns surged. The NYSE airlines index closed up 19.4% while planemaker Boeing Co jumped 13.7%. Cruise line operator Carnival Corp finished up more than 39%.

In contrast, the consumer discretionary sector was the S&P's biggest sector decliner with a 1.6% loss while the technology sector ended the day 0.7% lower, pushing the Nasdaq lower for the session.

Companies that had outperformed during the pandemic as they were seen as "stay-at-home" winners fell sharply.

Netflix Inc fell 8.5% and Amazon.com Inc declined 5% while Zoom Video tumbled 17.3% and exercise bike maker Peloton Interactive Inc PTON.O> plunged 20.3% to limit the Nasdaq's advance.

"Stocks like tech are being served up as a form of proceeds to fund the purchase of pro-cyclical stocks that would stand to benefit from the economic reopening that could be accelerated by way of a vaccine," said Mark Luschini, chief investment strategist at Janney Montgomery Scott in Philadelphia.

Stocks around the world had already been gaining ground before the vaccine data pushed equities even higher as expectations of better global trade ties and more monetary stimulus under U.S. President-elect Biden was already lifting demand for risky assets.

Pfizer shares closed up 7.7% after soaring as much as 15.4% during the session. But another drugmaker Biogen Inc slumped 28.2% as a panel of experts to the U.S. health regulator voted against the drugmaker's experimental Alzheimer's treatment.

On U.S. exchanges 17.2 million shares changed hands in the market's busiest trading session since June and compared with the 9.68 billion average for the last 20 sessions.

Advancing issues outnumbered declining ones on the NYSE by a 3.22-to-1 ratio; on Nasdaq, a 1.96-to-1 ratio favored advancers.

The S&P 500 posted 140 new 52-week highs and 1 new low; the Nasdaq Composite recorded 246 new highs and 25 new lows.

(Additional reporting by Caroline Valetkevitch in New York, Medha Singh and Shivani Kumaresan in Bengaluru; Editing by Shounak Dasgupta, Arun Koyyur, Patrick Graham and Tom Brown)