US STOCKS-S&P 500 rises on vaccine roll-out, mega-M&A activity

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* Alibaba sinks on Chinese regulatory ire
* Amazon leads gains in consumer discretionary
* Alexion Pharma among top boosts on AstraZeneca offer
* Indexes: Dow +0.04%, S&P 500 +0.20%, Nasdaq +0.96%

(Updates with afternoon trading)
By Karen Pierog and Noel Randewich
Dec 14 (Reuters) - The S&P 500 rose on Monday after the
launch of a nationwide 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.
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 led gains
among sector indexes, with Amazon AMZN.O rising 2%.
The S&P 500 gave up most of its gains after rising almost
1%. The index has surged 14% 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
about 30% 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 fell more than
7%. The Dow Jones Industrial Average .DJI was up 0.04% at
30,059.53 points, while the S&P 500 .SPX gained 0.20% to
3,670.83.
The Nasdaq Composite .IXIC added 0.96% to 12,496.99.
Uncertainty over more fiscal stimulus cut short a rally in
U.S. stocks after the Senate last week approved a one-week
extension of federal funding to avoid a government shutdown and
allow more time for negotiations on coronavirus relief and an
overarching spending bill. The focus was also 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 shed
almost 3% 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 rose 4% as
anticipation of its addition to the S&P 500 benchmark next week
offset a report of production delays. Walt Disney Co DIS.N fell about 2.5% after rallying on
Friday and was the biggest drag on the Dow after BMO Capital
Markets downgraded the stock.
Advancing issues outnumbered declining ones on the NYSE by a
1.05-to-1 ratio; on Nasdaq, a 1.29-to-1 ratio favored advancers.
The S&P 500 posted 25 new 52-week highs and no new lows; the
Nasdaq Composite recorded 205 new highs and 12 new lows.