You first take a Hackerrank test with several math questions and a DP programming question. They give you 3 hours and the test wasn't hard; I finished in around 2 hours. Then there's a standard behavioral test. If you pass this, they invite you to an onsite. In the morning, you take a 30 min sequences test, followed by a 2 hour written test that is mostly probability. This test was difficult and the time was tight although I felt I did alright. Afterwards, there's a one hour technical - they asked me four problems that were all probability and brainteasers that are around average difficulty. I think I did well on it. Then there's a lunch with two quants and in the afternoon, they go over your test and there's a one hour behavioral where they talk about your prior experiences. I didn't get an offer but overall I had a positive opinion of the company, and the recruiting process was very streamlined and efficient.

Very smooth, the HR just asked me why Optiver, why quant, what is your strength and weakness, what is the career plan in the next 5 years, but I did not answer very perfect