A software developer accused of stealing data from finance company Capital One took files from over 30 other organisations, prosecutors claim.
The alleged thief, Paige Thompson, was arrested after reportedly talking online about taking Capital One data.
In court papers, the US Department of Justice claimed Paige Thompson had "terabytes" of data in her possession.
It said she had "intruded" into servers belonging to companies, schools and government agencies.
Further charges against Ms Thompson could result from the evidence gathered during a search of her home, it said.
The FBI was working to identify all those who had had data taken so it could alert them to the suspected theft.
And investigators were also looking at the types of information allegedly taken.
The DoJ said there was no evidence yet that Ms Thompson had tried to sell the data she had allegedly taken from Capital One.
Ms Thompson is a former employee of Amazon and is alleged to have taken data from cloud servers it runs.
The Capital One data breach involved personal information about more than 106 million of its customers.
Data taken included names, addresses and phone numbers of customers who had applied for credit cards and other financial services.
Capital One said no credit card information was taken in the breach.
The legal document added the theft had left Capital One facing more than 40 cases of legal action in the US and eight in Canada.
The DoJ filed its court papers in a bid to ensure Ms Thompson stays in prison until the trial centring on the Capital One data breach begins.
It claimed she had a history of mental illness and threatening behaviour that led to her being a "flight risk".
A hearing about the case is scheduled to take place on 15 August.