The Competition and Markets Authority has raised questions over the merger between the global internet retailing partner, Yoox and high-end e-tailer, Net-a-Porter. The concerns revolve around reduced competition for UK shoppers who like to buy their luxury goods online.

The all-share merger between the two fashion powerhouseswas agreed earlier this year at the end of March.

The watchdog said it is considering whether the tie-up “may be expected to result, in a substantial lessening of competition within any market or markets in the United Kingdom for goods or services” and is inviting comments from “any interest party”.

The transaction between the two luxury goods purveyors would create the YOOX Net-a-Porter Group, an independent online retailer, with combined 2014 net revenues of almost £1bn, and the new online fashion giant could be valued at over £1.8bn.

Launched in 2000, Yoox is a multi-brand online fashion store with operations in China, Europe, the U.S. China and Hong Kong.

Net-a-Porter was founded the same year, with Richemont acquiring a majority stake in for around £225m. Shares in the conglomerate slipped after it released a statement confirming the talks, while Yoox‘s rose.

Emily Thornhill