Nov. 10 (Bloomberg) -- Thomson Reuters Corp., the news and data provider created in a merger last year, faces a European Union antitrust probe into possible restrictions on competitors’ use of identification codes for real-time market data feeds.

The probe will focus on whether Thomson Reuters prevents clients from translating Reuters instrument codes to alternative identification codes of rival data-feed suppliers, a process known as “mapping,” the European Commission, the EU’s antitrust regulator, said in a statement today from Brussels.

“Without the possibility of such mapping, customers may potentially be ‘locked’-in to working with Thomson Reuters because replacing Reuters instrument codes by reconfiguring or by rewriting their software applications can be a long and costly procedure,” the commission said.

The probe is the EU’s second into financial information providers this year after the regulator said in January that it would review how Standard & Poor’s charges customers for the use of certain codes in databases. Thomson Reuters said last week that third-quarter profit dropped 59 percent on declining revenue at its sales and trading business and legal division.

Thomson Reuters said in a statement that it received an EU questionnaire Nov. 3 and is cooperating with the probe.

“Thomson Reuters data is reliably and consistently identified by a managed code, which we create and maintain to enable navigation of the company’s global content,” the New York-based company said in the e-mailed statement. “Our customers are at the heart of our business and we continue to work with them to explore how best to add value to our data services.”

The commission said it started the probe on its own initiative. Under EU rules, companies can be fined as much as 10 percent of annual sales for antitrust violations. Companies can appeal antitrust decisions at EU courts.

Bloomberg LP, the parent of Bloomberg News, competes with Thomson Reuters in selling financial and legal information and trading systems.

To contact the reporter on this story: Matthew Newman in Brussels at Mnewman6@bloomberg.net.

Last Updated: November 10, 2009 06:25 EST