Millennium Partners Data Breach Exposes Social Security Numbers

Millennium Partners, a New York-based real estate development firm formally known as Millennium Partners Management LLC, disclosed a data breach involving the personal information of some of its customers and employees.

Millennium Partners discovered the breach on April 27, 2026, and posted a notice of the data security incident on Sept. 16, 2026.

The breach began when an unauthorized party gained access to Millennium Partners' systems at various times between April 24, 2026, and April 26, 2026. The company discovered a network disruption on April 27, 2026.

Shortly after the discovery, a ransomware group known as The Gentlemen claimed responsibility for the attack. On May 5, 2026, the group posted on the dark web Tor network, stating that it had obtained the organization's data and intended to publish it within eight to nine days.

On July 9, 2026, Millennium Partners confirmed that personal data belonging to some customers and employees stored on its network had been accessed and acquired by the unauthorized party.

The type of personal information involved may have included Social Security numbers.

Millennium Partners' response to the breach

Millennium Partners established a toll-free call center through TransUnion. The call center can be reached at 1-800-405-6108 and is available from 8 a.m. to 8 p.m. Eastern time, Monday through Friday, excluding federal holidays. Individuals who believe their information may have been involved are encouraged to call with questions.

The company advised individuals to remain vigilant for signs of identity theft and fraud by reviewing account statements and credit reports for any suspicious or unusual activity.