EU competition commissioner Joaquin Almunia said that following market testing, he was unconvinced that Thomson Reuters was making it easy enough for customers to use alternative providers. The long-running competition case had now reached "a critical stage", he said.
The case concerns Reuters Investment Codes (RICs), which are alphanumerical codes used by the company and its customers within their data feeds to identify, navigate and retrieve a structured set of data.
The EU is investigating whether customers are effectively 'locked in' to Thomson Reuters RICs because of the potential costs of rewriting software if they need to connect to other data feeds in a complex market.
But Thomson Reuters recently proposed a number of concessions to permit clients additional usage rights for the RICs, and to assist them in mapping RICs to rival sources.
Thomson Reuters said in a statement to Computerworld UK that it was "analysing" the EU feedback.