The UK Competition and Markets Authority has opened an investigation into the proposed merger of Paddy Power and Betfair.

The CMA inquiry was launched Monday to consider whether the transaction creates a relevant merger situation under the Enterprise Act 2002 and, if so, whether this could result in a substantial lessening of competition within the United Kingdom.

As part of the inquiry, the CMA is inviting comments on the proposed transaction from interested parties, with the deadline for submission of comments expiring on November 20th, 2015.

The CMA is expected to reach an initial decision on the effect of the proposed merger by January 7th, 2016.

Shares in Betfair Group plc. (Co. Data) (LSE:BET) were trading up 0.77 per cent in London early Tuesday at 3,283 pence per share, while Paddy Power plc. (Co. Data) (LSE:PAP) gained 1.05 per cent to set a new 52-week high of €107.32 per share.