The UK competition watchdog launched an investigation into whether Amazon had a dominant position in the market and abused that position by distorting competition. 

The UK Competition Authority announced an antitrust investigation into Amazon in July 2022, focusing on the company's practices in its online marketplace, focusing on its use of third-party seller data, the criteria Amazon used to select which product and seller would be featured in it's Buy Box system, and how the company set the eligibility criteria for sellers to use the Prime label.

In November 2023, the CMA announced (pdf) that it had accepted binding commitments from Amazon to address these concerns, effectively concluding the investigation. 

These commitments included an agreement not to use non-public commercially sensitive data from third-party sellers for its own retail business decisions, and a pledge to treat all products equally when determining which to feature in the Buy Box, using objective and non-discriminatory criteria.

Amazon also agreed to allow third-party sellers to negotiate their own rates directly with Prime delivery service providers. And, to ensure compliance, Amazon was required to appoint an independent trustee overseen by the CMA.