The UK’s competition watchdog is probing The Stars Group’s US$4.7b acquisition of Sky Betting & Gaming (SBG).

On Tuesday, Canada’s The Stars Group (TSG) announced that it had completed its acquisition of SBG, which the company originally announced in April. On Wednesday, the Competition and Markets Authority (CMA) announced that it was “investigating the completed acquisition” and had served an initial enforcement order under section 72(2) of the Enterprise Act 2002.

The CMA kept mum about its specific concerns regarding the deal, which created the world’s largest publicly traded online gambling firm. The enforcement order did say the CMA was considering whether to make a reference under sections 22 and 33 of the Act, which deal with mergers resulting in “a substantial lessening of competition” in the marketplace.

The CMA has instructed the companies involved not to take any further action that leads to the integration of SBG’s business into TSG’s business, or to transfer ownership or control of either company’s business, or take any steps that impair the ability of either company to compete independently in any of the markets in which they both operate.