In December, a former Block employee, Jack Dorsey, downloaded data on about 8.2 million American Cash App users. The company disclosed this in a report to the SEC.
Block (formerly Square) said the breach was discovered recently.
«Although the worker had regular access to these data as part of his previous duties, in this case they were obtained without authorization after his departure», the report said.
The stolen information includes full names and brokerage account numbers, and in some cases the value and composition of portfolios. The data do not include logins, passwords, Social Security numbers, addresses and other personal information, Block said.
The company said it would notify all 8.2 million former and current clients about the breach. According to the quarterly report, the app has about 42 million users in the US and Europe.
Block will also contact law enforcement and notify regulators.
«It is difficult to predict future costs associated with this incident. While the company has not yet completed its investigation, based on the preliminary assessment and information currently available, Block does not believe at this time that the incident will have a material impact on its operations or financial results», the firm said.
Following news of the breach, the stock fell from around $145 to about $125 — a drop of nearly 14%. As of the time of writing, premarket trading valued the shares at $129.
In the fourth quarter of 2021, Block’s revenue from selling bitcoin through the Cash App amounted to $1.96 billion.
In March, the company disclosed some technical details of a cryptocurrency wallet under development.