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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 1.23%, S&P 1.64%, Nasdaq 2.23% (Adds comment, details; updates prices)
By Medha Singh and Devik Jain
Sept 14 (Reuters) - Wall Street's major indexes climbed on Monday on a boost from technology stocks while signs of progress in developing a COVID-19 vaccine and a spurt of multi-billion dollar deals also brightened the mood.
Nvidia Corp jumped 6.7% on plans to buy UK-based chip designer Arm from Japan's SoftBank Group Corp for as much as $40 billion, in a deal set to reshape the global semiconductor landscape.
The Philadelphia SE chip index rose 2.4%. All major S&P sectors were higher with technology leading the charge with a 2.3% increase.
Oracle surged 5.6% 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 in a deal structured as a partnership rather than an outright sale.
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 tail-end of last week seemed to indicate a continued wobble in market sentiment that appears to be finding some more solid footing this morning," said Yousef Abbasi, global market strategist at StoneX Group Inc in New York.
"Behind this, we have the positive developments on vaccines as well as an active merger Monday."
Amazon.com rose about 1.9% after the online shopping giant said it is hiring 100,000 more workers in its latest job spree for the United States this year - to keep pace with e-commerce demand that jumped during the pandemic.
Apple Inc, Facebook.com and Google-parent Alphabet Inc rose between 2.0% and 3.5%.
At 10:57 a.m. ET, the Dow Jones Industrial Average was up 341.08 points, or 1.23%, at 28,006.72, the S&P 500 was up 54.82 points, or 1.64%, at 3,395.79. The Nasdaq Composite was up 241.80 points, or 2.23%, at 11,095.34.
Sentiment got a lift on Monday after drugmaker AstraZeneca resumed its British clinical trials of its COVID-19 vaccine, one of the most advanced in development.
Pfizer Inc gained 2.0% after the drugmaker and German biotech firm BioNTech SE proposed to expand their Phase 3 pivotal COVID-19 vaccine trial to about 44,000 participants.
"Markets are becoming increasingly comfortable with the notion that we may be moving towards a safe and effective vaccine, perhaps as early as the end of 2020, but at least into early 2021," said Quincy Krosby, chief market strategist at Prudential Financial in Newark, New Jersey.
Later this week, investors will focus on the Federal Reserve's last policy meeting before the Nov. 3 U.S. presidential elections.
Gilead Sciences Inc slipped 3.9% as it said would acquire biotech company Immunomedics Inc for $21 billion, a move that will strengthen its cancer portfolio by gaining access to a promising drug.
Advancing issues outnumbered decliners by a 4.36-to-1 ratio on the NYSE and by a 3.61-to-1 ratio on the Nasdaq.
The S&P index recorded 10 new 52-week highs and no new low, while the Nasdaq recorded 35 new highs and 14 new lows. (Reporting by Medha Singh and Devik Jain in Bengaluru; Editing by Saumyadeb Chakrabarty and Maju Samuel)