I had many in-person interviews and met most of the key staff. Like other candidates reporting their interview experiences here, I was asked many, many questions relating to extremely detailed specifics of the trading strategies I was involved in at my former employer, despite the interviewers often starting out by saying "obviously I don't want you to give away any IP about your strategies". It was very hard to answer the questions in a way that reflected positively on my candidacy without giving away confidential information, and I concluded in the end that their primary aim was, in fact, to extract knowledge of working strategies. Despite that, the interviewers were very congenial for the most part. I suppose this is all to be expected given the founding story of the company: Malyshev was successfully sued by Citadel for various breaches of his employment agreement, and you can find the legal documents describing the case on the web.
Also, I heard bad things about the company from another source, that the process they use for deciding bonuses is not well regarded by current employees, and that many of them are unhappy and looking to leave. I didn't pursue the process further.
