US STOCKS-Wall Street gains 1% on deal news, vaccine hopes

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* Nvidia climbs on $40 bln deal for chip designer Arm
* Pfizer, BioNTech expand late-stage COVID-19 vaccine trial
* Oracle surges on partnership with TikTok parent
* Indexes up: Dow 1.2%, S&P 1.3%, Nasdaq 1.6%

(Updates to late afternoon)
By Caroline Valetkevitch
Sept 14 (Reuters) - U.S. stocks were up more than 1% on
Monday afternoon as signs of progress in developing a COVID-19
vaccine and a spurt of multibillion-dollar deals lifted investor
optimism.
Nvidia Corp NVDA.O jumped 5.0% on plans to buy UK-based
chip designer Arm from Japan's SoftBank Group Corp 9984.T for
as much as $40 billion, in a deal set to reshape the global
semiconductor landscape. The Philadelphia SE chip index .SOX rose 1.9.
Oracle ORCL.N surged 5.0% as the cloud services company
said it would team up with China's ByteDance to keep TikTok
operating in the United States, beating Microsoft Corp MSFT.O
in a deal structured as a partnership rather than an outright
sale. Merger and vaccine-related news has "really lifted the
market," said Paul Nolte, portfolio manager at Kingsview
Investment Management in Chicago.
He said value-related areas of the market were holding up
well, continuing a recent trend. "It leads us to believe the
rotation we've been seeing out of tech to other parts of the
market is likely to continue."
U.S. stocks are coming off of two straight weeks of losses
as investors sold heavyweight technology shares that had powered
the benchmark index to record highs in a dramatic recovery from
its March lows.
The Dow Jones Industrial Average .DJI rose 364.6 points,
or 1.32%, to 28,030.24, the S&P 500 .SPX gained 46.15 points,
or 1.38%, to 3,387.12 and the Nasdaq Composite .IXIC added
182.54 points, or 1.68%, to 11,036.08.
All of the S&P 500 sectors were higher, and tech-related
heavyweights Apple Inc AAPL.O , Facebook.com FB.O and
Google-parent Alphabet Inc GOOGL.O were higher.
Tesla Inc's shares TSLA.O rebounded nearly 10%, recovering
after losses last week. Sentiment also got a lift on Monday after drugmaker
AstraZeneca AZN.L resumed its British clinical trials of its
COVID-19 vaccine, one of the most advanced in development.
MKTS/GLOB
Pfizer Inc PFE.N gained 3.4% after the drugmaker and
German biotech firm BioNTech SE 22UAy.F proposed to expand
their Phase 3 pivotal COVID-19 vaccine trial to about 44,000
participants. Later this week, investors will focus on the Federal
Reserve's last policy meeting before the Nov. 3 U.S.
presidential elections.
Immunomedics Inc's shares IMMU.O jumped after Gilead
Sciences Inc's GILD.O $21 billion buyout deal, which is a
steep premium to the biotech company's closing price on Friday.
Gilead gained 3.1%. Seattle Genetics SGEN.O gained 13% after Merck & Co Inc
MRK.N said it would buy $1 billion worth of equity stake in to
co-develop and sell the smaller drugmaker's cancer therapy.
Advancing issues outnumbered declining ones on the NYSE by a
4.52-to-1 ratio
The S&P 500 posted 11 new 52-week highs and no new lows; the
Nasdaq Composite recorded 49 new highs and 18 new lows.