US STOCKS-S&P 500 ends down after vaccine roll-out, mega-M&A

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* Alibaba sinks on Chinese regulatory ire
* Amazon leads gains in consumer discretionary
* Alexion Pharma among top boosts on AstraZeneca offer

(Updates with close of trading)
By Karen Pierog and Noel Randewich
Dec 14 (Reuters) - The S&P 500 ended lower on Monday after
the launch of a COVID-19 vaccine campaign in the United States,
while Alexion Pharmaceuticals jumped on a $39 billion buyout
offer from AstraZeneca in one of the year's biggest deals.
The Dow Jones Industrial Average hit a record high before
ending lower, weighed down by Walt Disney DIS.N .
Administration of the vaccine developed by Pfizer PFE.N
and its German partner BioNTech BNTX.O began on Monday
following emergency-use approval from federal regulators last
week. The S&P 500 consumer discretionary index .SPLRCD was one
of the strongest gainers among sector indexes, lifted by a rise
in Amazon AMZN.O . The energy index .SPNY tumbled.
The S&P 500 gave up earlier gains of almost 1%. The index
has surged about 13% to record highs in 2020, despite the
pandemic, which has wrought economic devastation and killed more
than a million people.
"While the entire market is pleased, is optimistic, is
bullish about the arrival of the vaccine this morning into the
U.S., I think the average investor is realizing that this
roll-out, this distribution of the vaccine is not going to be a
silver bullet, is not going to go as fast as one hopes," said
Jake Dollarhide, chief executive officer of Longbow Asset
Management in Tulsa, Oklahoma.
Alexion Pharmaceuticals Inc ALXN.O was among the top
boosts to the S&P 500 .SPX and the Nasdaq .IXIC , surging to
a 4-1/2 year high after British drugmaker AstraZeneca AZN.L
AZN.O said it would buy the U.S. biotech firm. AstraZeneca's
U.S.-listed shares dropped. Walt Disney fell after BMO Capital Markets downgraded the
stock.
Unofficially, the Dow Jones Industrial Average .DJI fell
0.62% to end at 29,859.97 points, while the S&P 500 .SPX lost
0.44% to 3,647.33.
The Nasdaq Composite .IXIC climbed 0.5% to 12,440.04.
Investors were also watching the outlook for additional
coronavirus relief after the Senate last week approved a
one-week extension of federal funding to avoid a government
shutdown and allow more time for negotiations. Investors were also focused on early voting in a pair of
U.S. Senate races in Georgia that will determine control of the
chamber and heavily influence lawmaking. E-commerce company Alibaba Group Holding Ltd BABA.N dipped
after China warned its internet majors of more anti-trust
scrutiny, imposed fines and announced probes into deals
involving Alibaba and Tencent Holdings Ltd 0700.HK .
Electric-car maker Tesla Inc TSLA.O rallied as
anticipation of its addition to the S&P 500 benchmark next week
offset a report of production delays.