U.S. markets and stock ETFs jumped Monday on growing optimism over a developing coronavirus vaccine, along with support from multi-billion dollar deals in the making.

On Monday, the Invesco QQQ Trust (NASDAQ: QQQ) increased 1.8%, SPDR Dow Jones Industrial Average ETF (NYSEArca: DIA) was 1.4% higher and iShares Core S&P 500 ETF (NYSEArca: IVV) gained 1.4%.

Nvidia Corp strengthened on plans to acquire the 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, Reuters reports.

Additionally, Oracle shares surged after the cloud services company said it would partner with China’s ByteDance to keep TikTok going in the United States, outbidding Microsoft Corp in a deal structured as a partnership instead of simply buying out TikTok.

Meanwhile, sentiment rose after drugmaker AstraZeneca resumed British clinical trials of a Covid-19 vaccine, which is one of the most advanced in progress. Pfizer Inc shares gained after the drugmaker and German biotech firm BioNTech SE proposed to expand their own Phase 3 Covid-19 vaccine trial to about 44,000 participants in what appeared to be a sign of further progress to the end of the coronavirus pandemic.

Merger and vaccine-related news has “really lifted the market,” Paul Nolte, portfolio manager at Kingsview Investment Management, told Reuters.

Nevertheless, some observers still issued a word of caution, especially with political uncertainty surrounding the contentious U.S. presidential elections and ongoing concerns over the economic recovery.

“We’re shifting into an environment of lower returns and higher volatility and this is not inconsistent with that,” James McCormick, global head of desk strategy at NatWest Markets, told the Wall Street Journal. “I think the upside is going be a bit capped here until we get through some of these events and risks.”

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