The European Commission has prohibited Siemens' proposed acquisition of Alstom. An in-depth investigation by the Commission concluded that the merger would have harmed competition in markets for railway signalling systems and very high-speed trains.

The takeover would have combined Siemens' and Alstom's transport equipment and service activities in a new company fully controlled by Siemens. It would have brought together the two largest suppliers of various types of railway and metro signalling systems, as well as of rolling stock in Europe, both also with leading positions globally.

The merger would have created the undisputed market leader in some signalling markets and a dominant player in very high-speed trains. It would have significantly reduced competition in both these areas, depriving customers, including train operators and rail infrastructure managers of a choice of suppliers and products.

The remedies offered by Alstom and Siemens to address these concerns were considered inadequate to protect competition in the European railway industry.

Alstom has stated that it regrets this consideration of the remedies offered, describing them as extensive in scope and as having addressed all the concerns raised by the Commission in respect of signalling and very high speed trains.