"It is really an unprecedented and dramatic turn of events," said Alex Haffner, competition partner at UK law firm Fladgate.
Becket McGrath, a partner at Euclid Law, said it seemed like the CMA wanted a way out of an "uncomfortable position".
Still, with the larger $69 billion deal back on track, the two sides are now focused on modifying the deal to obtain regulatory approval.
Jonathan Compton, partner at law firm DMH Stallard and a specialist in competition law, said it was difficult to see what structural alterations the company could make.
Britain's competition regulator has not given any further clarification on its U-turn or the new investigation, including whether it would fit into its Phase 1 and 2 process, the latter of which can take up to a year.
Persons:
Alex Haffner, Becket McGrath, Jonathan Compton, DMH, Euclid's McGrath, Sarah Cardell, Paul Sandle, Muvija, Martin Coulter, Amy, Jo Crowley, Kate Holton
Organizations:
Microsoft, Activision, Markets Authority, CMA, European Union, Euclid Law, Thomson
Locations:
United States, Devika