I met the recruiter and some analysts at a career fair and interviewed the next day. The interview was mostly behavioral with some technical questions thrown in there. Pretty standard questions - why Fannie, what does Fannie do, describe the mortgage market. From what I can remember the technical Q's had to do with evaluating risk, WACC. The second round was a week or two later at the HQ in DC. Very cookie-cutter behavioral interviews broken into a few rounds. One round is a case study.