Trading activity is displayed on an electronic board on the floor of the New York Stock Exchange (NYSE) U.S., on Wednesday, Feb. 1, 2012. (Jin Lee/BLOOMBERG)

The New York Stock Exchange agreed to pay $5 million to settle charges that it provided real-time market information to proprietary customers before distributing it to the public at large, violating regulations that require fair access to market data.

The penalty is the first imposed against an exchange by the Securities and Exchange Commission, which alleges that the NYSE had given certain customers an “improper head start” on stock quotes and trades during a three-year stint starting June 2008.

In an administrative order filed Friday, the SEC attributed the problems to technical issues with the electronic feeds that the NYSE uses to distribute market data. Two of the feeds devoted to NYSE subscribers sent customized data out milliseconds or seconds before similar information was sent to a separate feed for the general public.

“Improper early access to market data, even measured in milliseconds, can in today’s markets be a real and substantial advantage that disproportionately disadvantages retail and long-term investors,” Robert Khuzami, director of the SEC’s enforcement division, said in a statement.

The SEC action is the latest attempt to curtail high-profile technical glitches that have disrupted the increasingly complex markets, including the fiasco linked to Knight Capital Group in August and the “flash crash” more than two years ago.

Although the SEC blasted the NYSE for failing to monitor its speeds, it did not cite any specific harm suffered by investors in this case or intentional misconduct by the company.

The NYSE did not admit or deny wrongdoing. Its parent company, NYSE Euronext, said the technology problems that led to the SEC investigation have been resolved.

“The timing differentials stemmed from technology issues, not from intentional wrongdoing by the exchange or any of its personnel,” Duncan Niederauer, NYSE Euronext’s chief executive, said in a statement.

The SEC spotted the timing issues as it was investigating the “flash crash” of May 6, 2010, when the Dow Jones industrial average plunged nearly 1,000 points in minutes and then quickly regained its losses.

By then, the NYSE had partially addressed some of the technical issues tied to its market data feeds. But the heavy volume of trading that day overloaded the system, creating especially bad delays that the SEC noticed. During two five-minute periods, the average delay for the feed used to relay stock quotes and trades to the public was 3.7 seconds and 5.3 seconds, respectively. By contrast, the processing time for the proprietary feeds were 2 milliseconds and under 16 milliseconds.

The SEC order said that the delays did not cause the flash crash.

The agency criticized the NYSE for failing to involve its compliance department in critical technology decisions. It also alleged that the exchange failed to retain computer files that included information about data transmissions, making it difficult for the exchange to determine when it experienced delays or how long those delays lasted.

As part of the settlement, the NYSE and NYSE Euronext must retain an independent consultant to review their systems and make sure they comply with federal regulations.

Though the penalty was historic, it was small. Experts who track the stock market said the SEC’s actions were most likely meant to put the exchanges on notice. The message, they said, is that these companies can’t put profit ahead of the law.

“They went light the first time” with the penalty, said Bernie McGinn, chief investment officer at Union Street Partners Value Fund in Alexandria. “Maybe the fines will start to go up. Now everyone’s been forewarned.”