The Fate of Vodafone-Three Merger Lies With One Key UK Regulator

It took more than a year for a long-anticipated merger of Vodafone Group Plc and CK Hutchison Holdings Ltd.’s Three to come together. And it could take just as long for the deal to clear the antitrust and national security hurdles to come.

The combination of Vodafone and Three, announced Wednesday, would form the UK’s largest mobile operator by revenue — which in and of itself will prove a tricky proposition to take to Britain’s Competition and Markets Authority. The agency has aggressively tackled antitrust issues in recent months, blockingin April Microsoft Corp.’s $69 billion takeover of game ...