Check out the companies making headlines in midday trading Monday:
Moderna — Moderna shares surged 11.8% after CEO Stephane Bancel said Monday it will take months to distribute a Covid vaccine specifically targeting the omicron variant, but a higher 100-microgram dose of the booster shot could be ready "right away." Bancel said it will take at least two weeks to study how the new variant's mutations impact the efficacy of current vaccines.
Twitter — Shares of the social media company fell 2.7% after news that CEO Jack Dorsey is stepping down, effective immediately. Parag Agrawal, the company's chief technology officer, will take over as chief executive. Dorsey was serving as both the CEO of Twitter and Square, his digital payments company. He will remain a member of the board until his term expires in 2022.
Merck — Shares of the pharmaceutical giant slid 5.3% after Citi downgraded Merck to neutral from buy. Citi said in a note to clients that disappointing data from two key drugs for Merck in recent weeks hurt its long-term earnings potential.
Ebay — The e-commerce giant lost more than 2% after announcing it's acquiring Sneaker Con Digital, the sneaker authentication business of the marketplace Sneaker Con. Ebay said the deal furthers its expansion strategy in sneakers and will give customers added confidence in their high-value item purchases. The companies signed and closed the deal on Nov. 24. Terms of the deal were not disclosed.
Bristol-Myers Squibb — Shares of the pharmaceutical company fell 3.3% even after the company announced its application for a psoriasis-treating drug called deucravacitinib was accepted by the Food and Drug Administration and European regulators validated its application.
Allbirds — The eco-friendly shoe stock dropped 4.7% after a mixed batch of initiations from Wall Street banks. Morgan Stanley and JPMorgan initiated coverage of Allbirds with neutral-equivalent ratings, citing concerns about the company's long-term growth potential.
Tesla — Shares of the electric vehicle maker rose 5% on news that CEO Elon Musk urged employees to prioritize "minimizing cost of deliveries" over expediting deliveries of cars to customers in order to hit end-of-quarter goals. Tesla is also closer to starting production at its first European factory in Germany, according to German auto news site Automobilwoche.
Coinbase — The cryptocurrency exchange's shares rose 5.3% as the price of bitcoin rebounded following a sell-off with the broader equities market on Friday. Other crypto-related equities got a lift too, with Microstrategy rising 4.9% and Silvergate Bank adding 5.8%.
Zoom Video — Shares of the video-conferencing fell less than a percent, paring back deeper losses from earlier in the day, as some of Friday's enthusiasm for the stay-at-home stocks cooled. Shares of the company rose nearly 6% in the prior session, as the omicron Covid-19 variant sparked investors to rotate into areas of the market that benefit when consumers are at home.
— CNBC's Jesse Pound, Pippa Stevens, Yun Li and Hannah Miao contributed reporting