Check out the companies making headlines midday Monday:

AstraZeneca — Shares of British pharmaceutical giant AstraZeneca fell more than 3% after the company said clinical trials showed its coronavirus vaccine has an average efficacy of 70% in preventing the virus. Its competitors Pfizer and Moderna previously said their Covid-19 vaccine candidates were more than 90% effective.

Regeneron — Regeneron gained as much as 3.9% after the Food and Drug Administration over the weekend granted an emergency use authorization for its antibody treatment REGN-COV2. Regeneron CEO Dr. Leonard Schleifer told CNBC Monday the company will provide the U.S. with 300,000 doses by early January.

Snap — Snap shares gained 3.2% after the social media company launched Spotlight, a feature to its Snapchat platform that functions like TikTok and Instagram Reels.

United Airlines, Carnival Corp. — Shares of airlines and cruise operators rose broadly amid optimism around a potentially strong economic recovery as more vaccine trials show promising results. United Airlines traded higher by 2.6%. Carnival Corp advanced 3.7%.

Gap — Shares of the retailer jumped more than 7% after JPMorgan upgraded the stock to an overweight rating. The firm said Old Navy is "benefitting larger picture from the disproportionate growth of 'value retail,'" while Athleta is "well positioned to capitalize on the athletic apparel sector growth." The firm raised its Dec. 2021 price target to $30, which is 64% above the stock's Friday closing price.

General Motors — Shares of the legacy automaker rose 2.3%, continuing their rise after GM's bullish projections about its electric future last week. If the stock finishes in positive territory Monday, it will be the fourth-straight positive session for GM.

Roku — Roku shares popped more than 5% after the company's price target was hiked by Needham. The firm raised its 12-month price target on the stock to $315 per share from $255 per share. That implies an upside of nearly 20% from its Friday closing price. Needham said Roku "benefits from long-term upside connected TV."

Foot Locker — Piper Sandler downgraded the retailer to an underweight rating, causing shares to slide nearly 1.5%. The firm said Foot Locker lacks near term visibility as Covid-19 cases rise, and that over the long term Nike's direct-to-consumer efforts could pressure the company.

Tesla — The electric vehicle company's stock continued its recent surge on Monday, gaining 5.9%. Wedbush raised its price target on the stock to $560 per share from $500, and the firm said it was optimistic about Tesla's upcoming Cybertruck and Model Y.

—CNBC's Pippa Stevens, Yun Li and Jesse Pound contributed to this report.