Novo Holdings' planned $16.5 billion purchase of Catalent (NYSE:CTLT) is being probed by the European antitrust regulator.

The European Commission has set a date of Dec. 6 to decide if its analysis of the combination will move to an in-depth review, according to a posting on the regulator's website.

Catalent (CTLT) and Novo Nordisk Foundation received a request for more information from the Federal Trade Commission in May on their planned deal.

In February, Catalent agreed to be acquired by Novo Holdings for $63.50 a share. Novo Holdings will then sell three Catalent manufacturing sites to Novo Nordisk (NVO), which should help increase production of the company’s hugely popular weight-loss drug, Wegovy.