Big Pharma has been big busy this week. On Monday, French pharma leviathan Sanofi purchased San Francisco-based immunology specialist company Principia Biopharma for $3.68 billion. Not to be outdone, Johnson & Johnson, one of the companies working on a COVID-19 vaccine with federal grants, announced it will purchase Cambridge, Massachusetts-based Momenta Pharmaceuticals for $6.5 billion. 

In the Sanofi deal, Weil, Gotshal & Manges represented Sanofi, with the firm's mergers and acquisitions chairman Michael Aiello and M&A partner Sachin Kohli leading the way.