Got through the Jane Street recruiter phone screen about six weeks ago. Wasn't sure what to expect from a quant firm recruiter so I took notes. Sharing them here in case it helps.
My screen was 30 minutes. Recruiter was sharp and pretty direct. No small talk warm-up, went straight in.
What they asked: Walk me through your background. (standard, but they interrupted with clarifying questions, specifically around technical projects) Why Jane Street, and why now? (they probed pretty hard on this. "we're a different kind of company, what specifically draws you" type of energy) What languages are you most comfortable in, and what's your comfort level with functional programming? (I answered honestly: solid Python/Go, limited FP. they seemed fine with that for a non-quant-dev role) What's a hard problem you've worked on recently? (not asking for the solution, asking what made it hard and how you thought about it) Questions for me?
What I noticed: they're explicitly checking for intellectual curiosity and honest self-assessment. One response I gave was "I'm not sure, but here's how I'd think about it" and the recruiter paused and said "good, that's a useful answer."
They were also surprisingly transparent about the process. Told me the timeline, what the next steps looked like, and explicitly said the coding screen is hard and to expect it to be harder than LeetCode mediums.
Timeline from phone screen to next step: about 10 days to hear back on whether I was moving to the online assessment. I moved forward.
If you're prepping: have a specific and honest answer ready for "why Jane Street." Generic "I love trading" won't land.