Capital One says data breach affected 100 million credit card applications
Here's the DOJ press release: Seattle Tech Worker Arrested for Data Theft Involving Large Financial Services Company
And Capital One's official page about it (including a separate FAQ page).
The (PDF) actual complaint document linked from the DOJ release is very short and readable too. The suspect made a lot of mistakes, and it shows the kind of information and story they can put together pretty easily now by just correlating activity across different sites that all keep histories.