They are very thorough in their interview process. The important things that it seemed to me like they were looking for were self-motivated, naturally smart, and quantitative-minded individuals. Having a working understanding of financial markets and what was currently happening was definitely a bonus. Also, they definitely take into account the ability to learn from mistakes. If you're wrong they will let you know and prod you in the right direction so heed their advice. They grill you so that they can see how you handle pressure environments since that is a major aspect of the position.