A shudder went through Wall Street on Friday after the revelation that Bloomberg News reporters had extracted subscribers’ private information through the company’s ubiquitous data terminals to break news.

The company confirmed that reporters at Bloomberg News, the journalism arm of Bloomberg L.P., had for years used the company’s terminals to monitor when subscribers had logged onto the service and to find out what types of functions, like the news wire, corporate bond trades or an equities index, they had looked at. Bloomberg terminals, which cost an average of more than $20,000 a year, are found in nearly every banking and trading company.

Bloomberg said the functions that allowed journalists to monitor subscribers were a mistake and were promptly disabled after Goldman Sachs complained that a Bloomberg reporter had, while inquiring about a partner’s employment status, pointed out that the partner had not logged onto his Bloomberg terminal lately.

The incident led to broader concerns about the line at Bloomberg between its lucrative terminal business and the hypercompetitive newsroom, threatening to undermine the credibility of both. In a secretive world that thrives on opacity, traders and financial firms jealously guard every speck of information about their activity to avoid tipping their hand on their trades and investments.

“On Wall Street, anonymity is critically important. Secrecy and the ability to cover one’s tracks is paramount,” said Michael J. Driscoll, a former senior trader at Bear Stearns who now teaches at Adelphi University. He added: “If Bloomberg reporters crossed that line, that’s an issue.”

The news gathering technique appears more widespread than the Goldman incident, which was first reported by The New York Post. A preliminary analysis at Bloomberg revealed that “several hundred” reporters had used the technique, a person briefed on the analysis said. (Bloomberg employs more than 2,400 journalists worldwide. A spokesman declined to comment on the analysis and said no reporters had been fired.)

The F.B.I. scolded several news media outlets on Wednesday for mistakenly reporting that an arrest had been made in the Boston Marathon bombing case, and warned that such unverified reporting could have “unintended consequences” for its investigation.

Numerous organizations, including The Associated Press, The Boston Globe and several local Boston television stations, erroneously reported Wednesday afternoon that an arrest had been made, citing unnamed law enforcement sources. Two of the most prominent reports came from CNN and the Fox News Channel, both the subject of widespread criticism last June after misreporting the result of the Supreme Court ruling on President Obama’s health care overhaul law.

CNN and Fox News spent about an hour discussing the news of an arrest with various correspondents and experts before backing off when they received further information.

NBC News held back on reporting news of an arrest during continuing coverage on its MSNBC cable channel. It reported that no arrest had been made and that no person had been firmly identified as under suspicion. (The New York Times did not report that there was a suspect or an arrest.)

The F.B.I. issued a statement later in the afternoon: “Over the past day and a half, there have been a number of press reports based on information from unofficial sources that has been inaccurate. Since these stories often have unintended consequences, we ask the media, particularly at this early stage of the investigation, to exercise caution and attempt to verify information through appropriate official channels before reporting.”

CNN broke news of an arrest at 1:45 p.m., with the correspondent John King citing law enforcement sources. About a half-hour earlier, Mr. King had reported what he called a “breakthrough in the identification of a suspect” and included details of a physical description.

“I was told by one of these sources, who is a law enforcement official, that this was a dark-skinned male,” Mr. King said.

By about 2:45, one of CNN’s law enforcement experts, Tom Fuentes, a former assistant director of the F.B.I., appeared on the air and reported that he had three sources who assured him no arrest had been made. The network issued a statement later in the afternoon that cited the three sources who had given CNN the information it used to break the news of the arrest: “CNN had three credible sources on both local and federal levels. Based on this information we reported our findings.”