The Competition and Markets Authority (CMA) is investigating the proposed buyout of a minority stake in E.ON by German utility RWE.
Under the agreement between the two companies, RWE is to sell its 76.8% stake in innogy for a resulting shareholding in E.ON of 16.67%.
The CMA is examining whether the merger could result in a “substantial lessening of competition within any market or markets in the United Kingdom for goods or services”.
It is inviting comments about any competition issues until 13th March 2019.
The acquisition is part of an asset swap deal which involves breaking up innogy and dividing its assets between parent company RWE and E.ON.
Earlier this month, E.ON submitted its application to the European Commission to acquire innogy.