The U.K. Competition and Markets Authority will investigate the acquisition of EMIS Group PLC by UnitedHealth Group Inc., it said Friday.
The CMA said it will investigate if the deal may result in a substantial lessening of competition, and set a deadline of March 17 for its phase-one decision.
The watchdog has invited the parties to comment by Feb. 3.
In June, Emis EMIS, -0.21% agreed to a 1.24 billion-pound ($ 1.54 billion) cash offer from UnitedHealth Group UNH, +1.71%.
Write to Michael Susin at michael.susin@wsj.com