Bloomberg was questioned last week over its journalists allegedly using confidential client data.
The New York Post reported that Bloomberg reporters had been caught using the financial news service's $20 000-a-year terminals to spy on Goldman Sachs's bankers.
The breach could be a major issue for Bloomberg, which makes most of its money from renting the terminals to traders. The company has now moved to block reporters from accessing confidential information. But it faces complaints from other Wall Street banks that believe they too were spied upon by reporters in a breach of confidentiality.
Sources at JPMorgan said they believe the news organisation may have used information considered to be confidential while pursuing stories about Bruno Iksil, the London trader blamed for huge losses at the bank last year.
More than 300 000 of the world's most influential people including top bankers, treasury officials and hedge fund managers have access to a Bloomberg terminal.
Almost all users are identified by name and their terminals are often highly tailored to give them access to the financial information they need. Access to the types of information those users are looking up would give a reporter invaluable insight.
Bankers said they believed the reporters had access not only to log-in information but also to whether the users had called the help desk. "I don't think anyone realised how much information the news desk had access to," said one Wall Street executive.
Confirmation
Goldman confirmed that it had recently confronted Bloomberg executives after it emerged that reporters could determine which of its employees had logged into the terminals and how many times they had used particular functions.
"We brought this matter to the attention of the news organisation, and senior management at the company assured us that they were taking immediate measures to address the problem," a Goldman spokesperson said. He declined to comment on specific incidents.
Bank sources told the Post that in one incident a Bloomberg reporter asked a bank executive whether a Goldman partner had left the firm, noting that he had not logged into his terminal for some time. Bloomberg said it had now moved to restrict journalists' access to log-in information and other data, including the types of functions they were accessing on the machines.
Former Bloomberg staff, speaking on condition of anonymity, described the company's culture as "porous". In early years, Bloomberg reporters would assist on the help desk and go on client pitches.
Bank executives were not keen to talk on the record. "Privacy is privacy. The fact that an organisation can, at the very least, monitor the whereabouts of our staff is clearly a concern," said one banker. — © Guardian News & Media 2013