By Peter Nurse

Investing.com -- Stocks in focus in premarket trade on Monday, December 19th. Please refresh for updates.

• Tesla (NASDAQ: TSLA) stock rose 3.3% after a poll Elon Musk instigated suggested he should stand back from his role as head of Twitter, in theory allowing him to devote more of his time to his role as CEO at the electric car manufacturer.

• Meta Platforms (NASDAQ: META) stock fell 1.2% after the Facebook parent was warned by the European Commission that it is breaching EU antitrust laws by distorting competition in markets for online classified advertising and abusing its dominant position.

• Moderna (NASDAQ: MRNA) stock rose 3.4% after Jefferies upgraded its stance on the drug maker to ‘buy’ from ‘hold’, citing the company’s opportunities in the field of cancer therapy.

• Aerojet Rocketdyne (NYSE: AJRD) stock rose 1.8% after L3Harris Technologies (NYSE: LHX), down 1.7%, agreed to pay $4.7 billion for the company, the maker of the surface-to-air Javelin missiles that have proved so effective in Ukraine this year.

• AstraZeneca (NASDAQ: AZN) ADRs fell 0.4% after the U.K.-Swedish pharma company said its Imfinzi cancer drug had failed to reach primary endpoints in the latest of a series of trials.
• Mesa Air (NASDAQ: MESA) stock rose 7.7% after the carrier said over the weekend it is finalizing an agreement to operate regional flights for United Airlines (NASDAQ: UAL), up 0.9%, after an announcement it will wind down flights for American Airlines (NASDAQ: AAL), up 0.6%, early next year.
• Warner Music (NASDAQ: WMG) rose 1.6% after Atlantic Equities upgraded its stance on the entertainment group to 'overweight' from 'neutral', saying it can continue to deliver growth in streaming despite the difficult macro situation.