Fidelity National Financial has been hit by a "cybersecurity incident" that forced it to block access to systems, leading to business disruptions.
In an SEC filing, FNF- which provides title insurance and transaction services to the real estate and mortgage industries - says that an unauthorised third party accessed certain systems and acquired credentials.
The firm moved to contain the problem by blocking access to some if its systems, which led to disruption to services.
"For example, the services we provide related to title insurance, escrow and other title-related services, mortgage transaction services, and technology to the real estate and mortgage industries, have been affected by these measures."
FNF has begun an investigation, called in experts and notified law enforcement.