Take a look at the top midday traders.

Pfizer — Shares jumped 1.9% after British regulators approved the use of Paxlovid, the drugmaker’s Covid-19 antiviral pill, for people over 18 with mild to moderate illness. U.S. Food and Drug Administration last week authorizedPaxlovid is recommended for those 12 or older who have mild-to-moderate Covid and are at greatest risk of being hospitalized. 

Carnival, Norwegian Cruise Line — Cruise line stocks continued to struggle after the Centers for Disease Control and Prevention on Thursday said Americans should not travel on cruisesAll, no matter your vaccination status. Carnival dropped 2.2%; Norwegian Cruise Line fell 2.3%, and Royal Caribbean was also affected.

Peloton — Shares of Peloton slumped 2.5% after JMP Securities downgraded the stock to market performThe market has outperformed. JMP stated that consumers are less interested in at-home gyms.

Coterra Energy — The oil company fell 2.4% on the final day of 2021. Coterra has announced that Kevin William Smith, vice president and chief tech officer of the company, sold almost 40,000 shares this week.

Novavax — Shares of the drugmaker fell more than 2% after news that it extended manufacturing agreements with Korea-based SK bioscience. Novavax received an emergency use permit for Covid-19 vaccines.

Didi — The Chinese ride-hailing company continued to decline into the end of the year, falling more than 9% on Friday. Didi was listed in June. However, the stock price has fallen since Chinese regulators cracked down.

— CNBC’s Jesse Pound and Yun Li contributed reporting