First round interview was an HR screening. Very basic fit questions asking you to describe your reactions to various situations you have faced. For example, "Talk about a time you failed at accomplishing a long time goal." Second round was on site at the 20th and Market office in Philadelphia. There were three 30 minute interviews of mostly technical questions. First person asked fairly simple math and statistics questions (e.g. Solve an integral using a trig substitution). Second interviewer asked coding questions (e.g. How can you minimize collisions in a hash structure). Third interviewer was the hiring manager who asked half fit questions and then some slightly more advanced statistics questions, like define a martingale and describe the use of sigma algebras.