M&A Monday in healthcare: Merck, Sanofi, UnitedHealth

M&A Monday in healthcare, with two of the deals involving cancer drugs.

Merck is buying ArQule for $2.7 billion. It's the latest move by a U.S. drug maker to buy targeted cancer therapies. The deal strengthens Merck's oncology business well before its blockbuster cancer drug Keytruda loses its market exclusivity in 2028. ArQule's crown jewel that Merck wants is a precision drug that tailors treatment to a patient's genetic profile.

California's biotech firm Synthorx is getting $2.5 billion in cash, selling itself to France's Sanofi. Synthorx focuses on therapies for people with cancer or auto-immune disorders. Sanofi is stepping up its drive to expand into cancer drugs under its new chief executive. Like Merck, Sanofi is also paying a rich premium.

UnitedHealth, by contrast, is buying Diplomat Pharmacy at a 31% discount. Diplomat has been losing customers in its pharmacy benefits management business due to intense competition.

Shares of acquirers Merck, Sanofi and UnitedHealth fell, while Arqule and Synthorx shares doubled in early trading. Diplomat shares plunged more than 30%.