Wall Street climbs on mega mergers, vaccine hopes

By Medha Singh and Devik Jain

(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 (NASDAQ:NVDA) Corp jumped 5.7% 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 2.1%. All major S&P sectors were higher with technology leading the charge with a 2.1% increase.

Oracle (NYSE:ORCL) surged 5.1% 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 (NASDAQ:MSFT) 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."

Apple Inc (NASDAQ:AAPL), Facebook (NASDAQ:FB).com and Google-parent Alphabet (NASDAQ:GOOGL) Inc rose between 1.6% and 2%.

Tesla (NASDAQ:TSLA) Inc's shares rebounded 8.4%, almost making up for all of its losses from last week.

At 12:23 p.m. ET, the Dow Jones Industrial Average was up 373.05 points, or 1.35%, at 28,038.69 and the S&P 500 was up 53.75 points, or 1.61%, at 3,394.72. The Nasdaq Composite was up 215.62 points, or 1.99%, at 11,069.16.

Sentiment got a lift on Monday after drugmaker AstraZeneca (NYSE:AZN) resumed its British clinical trials of its COVID-19 vaccine, one of the most advanced in development.

Pfizer Inc (NYSE:PFE) gained 3.3% after the drugmaker and German biotech firm BioNTech SE (NASDAQ:BNTX) 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 (NYSE:PRU) 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.

Immunomedics (NASDAQ:IMMU) Inc's shares more than doubled on Gilead Sciences Inc (NASDAQ:GILD)'s $21 billion buyout deal, which is a steep premium to the biotech company's closing price on Friday. Gilead gained 3.0%.

Seattle Genetics (NASDAQ:SGEN) gained 13% after Merck & Co Inc said it would buy $1 billion worth of equity stake in to co-develop and sell the smaller drugmaker's cancer therapy.

Immunomedics and Seattle Genetics pushed the Nasdaq biotech index up over 5%.

Advancing issues outnumbered decliners by a 4.90-to-1 ratio on the NYSE and by a 3.75-to-1 ratio on the Nasdaq.

The S&P index recorded 10 new 52-week highs and no new low, while the Nasdaq recorded 38 new highs and 15 new lows.