Reporters at Bloomberg News were trained to use a function on the company's financial data terminals that allowed them to view subscribers' contact information and, in some cases, monitor login activity in order to advance news coverage, more than half a dozen former employees said.
More than 315,000 Bloomberg subscribers worldwide use the terminals for instant market news, trading information and communication. Reporters at Bloomberg News, a separate division from the terminal business, were nonetheless told to use the terminals to get an edge in the competitive world of financial journalism where every second counts, according to these people, who spoke on the condition of anonymity because of the company's strict nondisclosure agreements.
The company acknowledged that at least one reporter had gained access to information on Goldman Sachs after the bank complained to the company last month. On Sunday, Ty Trippet, a Bloomberg spokesman, said that "reporters would not have been trained to improperly use any client data."
(Read More: Wall Street: How Much Does Bloomberg Know?)
Matthew Winkler, editor in chief of Bloomberg News, underscored that the practice was at one time commonplace. In an editorial published on Bloomberg View late Sunday night, he said the practice of allowing reporters access to limited subscriber information dated back to the inception of the news arm of the giant financial information company founded by Michael R. Bloomberg.
"The recent complaints relate to practices that are almost as old as Bloomberg News," Mr. Winkler said. "Some reporters have used the so-called terminal to obtain, as The Washington Post reported, 'mundane' facts such as logon information."
It was a striking admission from the man who wrote "The Bloomberg Way: A Guide for Reporters and Editors," considered among the quintessential handbooks on ethical business reporting.
In his editorial, Mr. Winkler apologized for the practices that had taken place in the newsroom for decades. "Our clients are right," he said. "Our reporters should not have access to any data considered proprietary. I am sorry they did. The error is inexcusable."
Bloomberg's more than 2,400 journalists go through hours of compulsory training on how to use the superfast data-splicing terminals, and several former employees said that training included informal tips on how to use a function called UUID to locate sources who were also subscribers.
The sheer amount of data available on the terminals created a dynamic in the Bloomberg newsroom in which some reporters favored breaking news over strict subscriber confidentiality, former reporters said.
"There was always a discussion in the newsroom of how to use the terminals to break news," said one former Bloomberg journalist. "That's where it gets nuanced because I'm sure that in encouraging people to break news, Matt did not mean in this way," this person added, referring to Mr. Winkler.
On Friday, Mr. Winkler reminded reporters of the company's policy that prohibits journalists from discussing nonpublic Bloomberg documents and proprietary information about the company and its clients in their reporting. Last month, he contacted Goldman Sachs to apologize after the bank had complained about the reporting technique.
Bloomberg reporters also are accused of monitoring JPMorgan Chase executives' login information last summer, when the bank suffered a multibillion-dollar trading loss, according to people briefed on the situation. The bank never formally complained to Bloomberg representatives about the practice.