Recruiter reached out on LinkedIn and conducted a phone screen. Then scheduled a one-round "mini-case" interview over Zoom which was much like the profitability practice cases they provided, with a credit card scenario. Made it to power day shortly afterwards, which was 3 interviews for me.
First two interviews were cases again, with a little bit of behavioral stuff beforehand. First case was easy, a more straightforward profitability case about credit cards again. Second case was about more complicated and was about amusement parks. I found this one to be more challenging bc it requires you to keep track of several variables and keep all of your calculations organized. Ended up using 3 sheets of paper.
3rd case was a product case where they asked me to come up with 10 improvements to a lunchbox. Then they asked me to think of a digital product and we discussed the user base, revenue streams, and potential improvements. Didn't find it overly difficult but requires you to work with interviewer a bit more.
I received a call from the recruiter after the 3rd power day interview to let me know I would not be getting a 4th interview.
I did not consider the cases to be unfairly difficult, but they were a bit tricky to prepare for since most practice cases don't come in that format. My best piece of advice is to be very deliberate about calculations and staying organized.
From a personal perspective, I found my experience to be very dry, stiff, and rude at times. My recruiter was often very snippy and rude to me, and was not particularly helpful with the process, even calling me two different times two weeks apart to let me know I did not pass the interview. 3/4 of my interviewers were very stiff and rote, and it did not make for a very easygoing interview experience, nor did it make me very excited to work at Capital One. They are not really interested in getting to know you as a person, it's more about passing their test.
This process is very quantitative and exam-like. To others preparing, I would de-emphasize the personal/behavioral aspects of interview prep and just try to nail the case math and stay calm under pressure.