Danish pharmaceutical giant Novo Nordisk fell as much as 3.8 percent on Monday after Citi highlighted signs of waning momentum for the company's Wegovy tablet, Bloomberg News reports.

According to Citi, while the launch was initially robust, signs of a slowdown have begun to emerge. The bank also estimates that Eli Lilly's rival tablet, Foundayo, could gain traction when television advertising commences during the third quarter.

Barclays stated on Friday, citing IQVIA data, that prescriptions for oral Wegovy fell 4.4 percent during the week ending May 8 compared to the previous week.

Despite Monday's decline, Novo Nordisk shares have climbed 26 percent since hitting their year-to-date low on March 27.