• Information about Wednesday's critical consumer price index release circulated a half-hour early on the Bureau of Labor Statistics website.
• "BLS takes its data security seriously and is conducting a full investigation into its procedures and controls to ensure the incident is not repeated," the bureau said.
• There was little unusual market activity in the half-hour prior, indicating that the early release was not widely seen.

Information about Wednesday's critical consumer price index release circulated early on the Bureau of Labor Statistics website, according to a statement from the agency.

"In advance of [Wednesday's] CPI and Real Earnings releases, BLS inadvertently loaded a subset of files to the website approximately 30 minutes prior to the release," the BLS said in a brief statement.

The statement provided few details but noted that the Labor Department agency has notified the Office of Management and Budget and the department's Office of the Inspector General.

"BLS takes its data security seriously and is conducting a full investigation into its procedures and controls to ensure the incident is not repeated," the bureau said in its statement.

There was no other information provided concerning the early release of the CPI, a key inflation indicator that showed another increase in April, though slightly less than what the Wall Street consensus had anticipated. BLS officials did not immediately respond to a request for additional comment Thursday morning.

Stock market futures rallied after the 8:30 a.m. ET release, though there was little unusual activity in the half-hour prior, indicating that the early release was not widely seen and did not materially impact trading.

"It was weird because usually you're watching all the ticks beforehand and I didn't notice anything unusual, so I wonder to what extent it mattered," said Peter Boockvar, chief investment officer at the Bleakley Advisory Group. "There was nothing that I see that helps to explain any trading that went on beforehand."

The BLS several years ago modified the way it releases the data. Previously, it had provided media members advance copies under a lock-up at the bureau's Washington, D.C. office for release promptly at 8:30 a.m.

However, department officials during the Trump administration had expressed concerns that clients of some outlets in the lock-up were getting an unfair trading advantage through the system and terminated the arrangement. The information now is provided on the website around 8:30, with no pre-release.

"You always have to wonder who screwed this up," Boockvar said. "I don't think it's something persistent. It seems like a one-off."

The all-items CPI measure of goods and services throughout the sprawling U.S. economy indicated a monthly increase of 0.3%, slightly below the 0.4% estimate, and a 12-month rate of 3.4%.

Core inflation, which excludes food and energy, ran at a 0.3% rate monthly rate and 3.6% annually, the lowest since April 2022. Stocks closed sharply higher on Wednesday.