By Foo Yun Chee and Andreas Framke
BRUSSELS/FRANKFURT (Reuters) - Deutsche Bank
The European Commission did not name the banks, which could face fines up to 10 percent of their global turnover if found guilty of breaching EU antitrust rules.
Deutsche Bank said it had proactively cooperated with the Commission's investigation and did not expect a financial penalty. Whistleblowers are not sanctioned under EU rules.
The Commission said its investigation focused on the conduct of certain traders at the four banks.
"The four banks exchanged commercially sensitive information and coordinated on prices concerning U.S. dollar denominated supra-sovereign, sovereign and agency bonds, known as 'SA bonds'," it said.
"These contacts would have taken place mainly through online chatrooms."
Regulators worldwide have penalised the financial industry billions of euros in recent years for rigging various financial benchmarks.
(Reporting by Foo Yun Chee in Brussels and Andreas Framke and Arno Schuetze in Frankfurt; editing by Jane Merriman)