Check out the companies making headlines in midday trading.

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. The U.S. Food and Drug Administration last week authorized the use of Paxlovid for patients 12 and up with mild to moderate Covid who are most likely to end up hospitalized or not survive. 

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 cruises, regardless of vaccination status. Carnival fell 2.2%, Norwegian Cruise Line retreated 2.3% and Royal Caribbean also dipped.

Peloton — Shares of Peloton slumped 2.5% after JMP Securities downgraded the stock to market perform from market outperform. JMP said consumer interest is waning in the at-home fitness company.

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

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

Didi — The Chinese ride-hailing company continued to decline into the end of the year, falling more than 9% on Friday. Didi went public in June, but the stock has since sunk as Chinese regulators have cracked down on the company.

— CNBC’s Jesse Pound and Yun Li contributed reporting