Marquis, a technology company used by hundreds of banks to analyze and visualize their customers’ data, says hundreds of thousands of people had their personal and sensitive financial information stolen in a ransomware attack last year.

The Plano, Texas-based fintech company is notifying at least 672,075 people that hackers stole their information during the August 2025 cyberattack, according to a listing with Maine’s attorney general’s office.

More than half of all those affected live in Texas, according to a separate data breach notice filed in the state.

The disclosure is the fullest picture yet of the number of people affected by the breach, which has not been previously reported.

The breach allowed hackers to steal banking customers’ names, dates of birth, and postal addresses. The hackers also stole customers’ financial information, such as bank accounts, debit, and credit card numbers. Marquis said the hackers also took customers’ Social Security numbers.

The fintech company sued its firewall provider, SonicWall, in February, accusing the company of security failings that allowed hackers to steal critical information about its firewalls, which hackers then used to compromise Marquis’ network, steal data, and deploy ransomware.

In its lawsuit, Marquis said SonicWall created a vulnerability that allowed hackers to steal its customers’ firewall configuration backup files, including Marquis’ own.

Marquis did not immediately comment when contacted by TechCrunch.