The Competition and Markets Authority (CMA) today said it was considering whether the £1.3bn merger between Slug and Lettuce-owner Stonegate and pub chain Ei Group would lessen competition.
The watchdog invited comments on the deal from any relevant party by 25 October.
It said it was “considering whether it is or may be the case that this transaction has resulted in the creation of a relevant merger situation…and if so, whether the creation of that situation has resulted, or may be expected to result, in a substantial lessening of competition within any market or markets in the United Kingdom for goods or services.”
In July Stonegate, which also owns pub chains Walkabout and Yates, said it had bought its larger rival, offering 285p in cash for each Ei share, a 38 per cent premium.
The deal values Ei, which owns more than 4,000 pubs, at £2.97bn including debt.
Last month shareholders in both companies voted to approve the deal.
In August, UK pub and brewery chain Greene King agreed a £2.7bn takeover deal with Hong Kong’s CK Asset Holdings (CKA).
Shareholders approved that deal on Wednesday.
Ei Group and Stonegate declined to comment.