I received an email a day after I submitted the application to take an aptitude test, consisting of logic games and brain teasers. A few days later, I was contacted to setup an HR interview, which was about how I got to be interested in IT, Optiver, and how I work under pressure. A week later, I was emailed again asking me to write about a technical prompt for a non-technical audience, and I submitted it a week later. After 3 days, I was emailed saying they were impressed with my qualifications, but wasn't the right fit for the job. Even though they did not extend me an offer, I really appreciate their speed on getting back to me at each stage of the process.

Applied through website, received an email to set up a phone interview the next week. Took an aptitude test after phone interview, then was invited onsite. Onsite interview consisted of 3 behavioral interviews, a design interview and a technical interview all back to back except lunch between 4&5. Technical interview seemed very programming specific for a position described as "no IT experience required". Pretty friendly office atmosphere.