It has been reported today that for the Ladbrokes/Gala Coral merger to go ahead, the combined company may have to dispose of hundreds of shops.
The CMA said that about 350 to 400 shops may have to be sold "for the merger to be conditionally cleared".
Currently Gala Coral operate around 1,850 shops in Great Britain and Ladbrokes have 2,154 shops in Great Britain and 77 in Northern Ireland, making the combined group larger than William Hill who is the current market leader.
Chairing the CMA’s inquiry, Martin Cave, said: "We've provisionally found that the merger between two of the largest bookmakers in the country may be expected to reduce competition and choice for customers in a large number of local areas.
"Although online betting has grown substantially in recent years, the evidence we've seen confirms that a large number of customers still choose to bet in shops - and many would continue to do so after the merger.
"For these customers, competition comes from the choice of shops in their local area and it's they who could lose out from any reduction of competition and choice."
Head of equity research at Hargreaves Lansdown, Steve Clayton, said: "We expect substantial cost saving will be possible because there will be vast areas of overlap and unnecessary duplication of functions across the combined business."
Current private equity owners will own 48.25% of the new company’s shares with the remainder being held by Ladbrokes shareholders.