Terminals never allowed journalists to see specific securities or trades, but even general hints of what users are searching could provide a glimpse into Wall Street’s thinking — powerful currency in the competitive world of financial journalism. Daniel L. Doctoroff, chief executive of Bloomberg L.P. and a close confidant to the company’s founder, Michael R. Bloomberg, said in a memo to employees that “client trust is our highest priority and the cornerstone of our business.” Mr. Bloomberg stepped away from day-to-day operations when he became mayor of New York City.

Last month, the company further centralized its data security efforts, including appointing Steve Ross, a senior executive, to the newly created role of client data compliance officer.

“To be clear, the limited customer relationship data previously available to our reporters never included access to our trading, portfolio, monitor, blotter or other related systems or our clients’ messages,” Mr. Doctoroff said. He posted a damage control message to clients on the Bloomberg terminal and blog, calling the reporting practice a “mistake.”

Similar problems, which became public on Friday, started at JPMorgan Chase last summer, when the bank suffered a multibillion-dollar trading loss. Some Bloomberg reporters called the bank, people briefed on the call said, to question whether the traders responsible for the loss had been fired. They cited the fact that the traders had gone silent on the terminal. The bank, the people said, objected to the reporting technique, but did not formally reach out to Bloomberg executives to complain. Yet bank officials soon discovered that other Bloomberg reporters were using the approach on other stories unrelated to the trading loss.

When Goldman raised the issue with Bloomberg last month, the media company dispatched senior sales executives to Goldman’s Lower Manhattan headquarters, according to people briefed on the matter. The Bloomberg officials assured top bank executives, including Gary D. Cohn, the firm’s president and chief operating officer, that the problem would be resolved. “We brought this matter to the attention of the news organization, and senior management at the company assured us that they were taking immediate measures to address the problem,” a bank spokesman said.

Matt Winkler, editor in chief of Bloomberg News, also contacted Goldman to apologize for the incident. In a meeting on Friday, he reminded reporters of the company’s policy about terminal use and the employee confidentiality agreement.

Jonathan Corpina, a managing partner at Meridian Equity Partners, said the incident was a reminder that nothing — not even the seemingly secure Bloomberg terminal — was private. “It concerns people that what they are doing is being watched and monitored by people who shouldn’t be watching and monitoring it,” Mr. Corpina said.