Jane Street Final Round - What to Expect

kadgeratnum's picture
Rank: Monkey | 36

After going through the interview process, the OP shared the final round interview experience with readers of WSO. Check it out below.

Jane Street Capital Interview Process

Before the interview I went through five phone interviews before they invited me down, and I think they would have kept going except that I had an exploding offer coming up so I told them its final round or nothing. Every time I thought I had finally messed up the interview to the point where they wouldn't invite me back, but every time hr contacted me with the next date. When they say 'we aren't looking for the right answer so much as how you think about a problem', they mean it.

Preparation for the Final Round Jane Street Interview

Before the final round they send you a sheet outlining the basics of trading terminology. What bid and ask mean, as well as how to properly phrase that you would like to make a trade and at what price. My first pearl of wisdom is to study the shit out of this sheet.

If you have had trading experience before, great, but most applicants to Jane Street are, like me, math or other STEM majors so have not seen these terms or if they have certainly have not used them in a real time environment. As a note: I had taken finance courses and knew what these definitions actually meant, but there is a HUGE difference between being able to pass an econ exam and being able to rattle off a trade without thinking about it.

The last thing you want is to be committing mental capacity to figuring out if you want to give your bid or your ask price first when you should be fully committed to doing three digit fraction multiplication. Even worse, if you get confused and phrase the trade incorrectly the interviewer will not be afraid to crush you and take a highly unfavorable trade (for example by selling to you at the price you meant to give as your ask price). You should have a couple days between getting this sheet and the final round, use that time and don't wait until you were sitting around in the hotel the night before like me.

What Happens At A Final Round Jane Street Capital Interview?

At the final round itself you are given 100 poker chips at the start of the day. Over the course of the next 4-6 hour long interviews (I only had four, but I think that's because I got cut after four - there were still people interviewing as I left) you have to use the chips to make bets on scenarios given to you. Some sources claim these scenarios can be as simple as 'make a market on the temperature in the room', I didn't get these questions and I'm guessing that they are reserved for internship interviews. I got much more difficult ones, that require a decent amount of math. You will need to use the trading terms to bet on the results you get. There is probability involved (for example a deck of cards or non-six sided die), so the more astute of you will notice that a better candidate may end up with fewer chips than one who bet and got lucky - don't worry Jane Street is fully aware of this and judge you based on what you bet and why, not how much you win. Therefore, the actual number of chips you end up with is irrelevant (to a degree -see below), so if you have 20 chips after getting very unlucky on reasonable bets, don't try to win it all back thinking you are below some magic cutoff, there really isn't one. It is best to just ignore the existence of the chips to the extend you can and think about each problem as just an isolated probability/brain teaser problem.

The biggest single thing to remember about your chips is to never go all in. They tell you at the start of their interview that in their job they make positive expected value bets, but to never do so if there is a chance of being wiped out. Therefore, keep in mind: if you are 99% sure of something it means that you are willing to bet 99 of your chips just to get one chip, and even if what you're betting on is a coin flip with only heads, it's not acceptable to take that bet (extreme example, the in-interview examples are much more subtle). This means that if you end up with single digit chips you will almost certainly not get an offer, since you bet in a way that 'wiped you out' (note I ended up with 87 and still didn't get an offer).

Not every interview depends on the chips - some are straight math questions. All the more reason to just ignore the chips since you don't want to be thinking "shit I only have 43 chips" during an interview that doesn't concern the chips at all - always stay focused.

Interview Questions for Jane Street Capital

In terms of specific questions they ask: I would recommend going on glassdoor and looking up interview questions for Jane Street and maybe some other prop shops (ex. SIG). I actually encountered some very similar to the ones I had seen there, but they have enough new material that you will not be able to memorize your way through the interview.

Jane Street Brainteasers

Finally, they do ask an unsolvable question (or rather, one that you need a PhD in probability to answer), so yeah those rumors are true. Not gonna tell you what it is (where's the fun in that?), but I had seen it online before my interview. The point of the questions is not to get it right, but to bet chips on how long you think it will take you to answer it (the prompt is deceptively easy). Now remember, if you bet on a 99% confidence interval, it means you are technically saying you would bet 99 chips that you will be able to solve it for the chance to win one chip.

JSC Interview Process

Jane Street's interview process can be intimidating, and Jane Street describes how to prepare below. They also offer a guide to research and trading roles that we have attached below.


Source: https://www.janestreet.com/2017/05/18/probability-...

Read More About Jane Street Capital in Our Company Database.

Read more about Jane Street Capital in another thread on WSO.

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PDF icon Jane Street Interview Guide1.22 MB

Comments (36)

Sep 3, 2012

hats off + sb

where are you employed now, if its not a secret?

Sep 3, 2012

.

Sep 3, 2012

i had a similar deal with Jane Street. they are a tough bunch of fuckers they are.

Sep 3, 2012

Nice write-up. As interesting as all that sounds, it sure makes me glad I got away from the mental math arms race.

Sep 4, 2012

can you elaborate on what level of math was required?

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Sep 4, 2012

That sounds bloody tough - but also really awesome!! Some of the other quant firms have much more free-flowing interviews.
At Two sigma , I was asked what my favourite part of high school maths was - and I said combinatorics. The next hour was non-stop bombardment with some of the toughest problems I have ever seen!!

I'd call JSC's interview better , only because the ability to solve complex math problems under pressure of time is only tangentially related to trading , but the ability to make bets/size bets/make markets under pressure - well that's just the fucking job description!
OP , do you remember any of the tough math problems they asked you? Would be fun to take a look!

Sep 4, 2012

thx a lot for the insightful write-up. just curious about jsc's recruiting process, did u just apply it online?

Sep 4, 2012

I have a question OP, what should you wear if you get invited? I have heard that a suit is not the best option with firms like Jane Street. So what where the candidates wearing that day?

Sep 4, 2012

Jane Street's interviews are far harder than the other companies you listed. I've interviewed with the other firms you listed and while they ask mainly things you can see coming (probability, mental math, etc.), Jane Street has all kinds of wild problems that really take you for a ride. Just check out Glassdoor - but given that you've passed the previous rounds, you should already know what you're dealing with.

Sep 4, 2012

Do either of you mind comment more on this company? They were at my school in the fall but for non-revenue generating roles according to my advisor.

Sep 4, 2012

Thanks for the advice. I found the interviews for other places (SIG, Optiver et al) to be different and less quantitative/math problem solving.

For example, here is a question for a final round interview at one of the firms: if you wanted to price an option, what would you need to know? How would you acquire this information?

So this seemed less quantitative and more focused on trading strategies. Is Jane Street purely math testing with some psychology/game theory thrown in? The three phone interviews had zero fit questions and nothing about financial instruments.

Sep 4, 2012

Almost all of the prop firms assume zero financial knowledge. Maybe just a bit for full time hires, unless you state that you know it. I've found that while they don't explicitly tell you to price an option, they may give you the same question, just implicitly. For example, I've been asked to price games where I had the choice to cash out, based on certain probabilities.

But you can assume your final round will be similar to your phone interviews, it's not like they'd be that dramatically different given they're at the same firm. I've just found that one can quite easily prepare for the other prop interviews given a background in basic probability and arithmetic, but for the Jane Street ones you need to be very good at problem solving (IMO, Putnam, etc.), that kind of thing.

Sep 4, 2012

I'm certainly not at IMO gold medalist/Putnam fellow level, but I'd like to think I am competent at quantitative problem solving. Also I thought quant hedge funds like DE Shaw, Two Sigma, et al picked up most of the olympiad folks who go into trading/finance.

Sep 4, 2012

They don't actually ask you IMO/Putnam level math do they? Is it just that they require you to think with that level of sophistication?

Sep 4, 2012

Dude, you had the phone screens

You know exactly what to expect

They aren't gonna bust a random A6 on you in the final round

    • 1
Sep 4, 2012

By the way, received an offer. Will be making a post for future reference.

Sep 4, 2012
ActuarialDerek:

By the way, received an offer. Will be making a post for future reference.

Would appreciate a post outlining their interview process, as well as the questions you received.

Congratulations!

Sep 4, 2012

base salary?

Sep 4, 2012

I've actually seen that post which is undoubtedly useful, but I was hoping for more example questions e.g. in early rounds you get asked things about expected number of dice throws and counting combinations of ants jumping around triangles, etc.

I hear that the final round questions are more open ended and often unsolved. Was hoping someone could give me related examples? Not really expecting people to regurgitate their whole interview, just would like to know the type of open ended stuff that is discussed.

Cheers

Sep 4, 2012

Should be all problem solving

Is this for an internship, full-time offer, or a contract offer?

Sep 4, 2012

I've never gotten to the last round when I was interviewing... but I heard from my friend that you play cards the final round

Sep 4, 2012

cool. it's for full time. but i guess this doesn't make much difference does it?
@runningcitylikediddy: what do you mean by 'play cards'? do u mean like poker and calculating odds?
cheers

Sep 4, 2012

The focus will be on problem solving and brainteasers, but you should of course be ready to answer generic fit questions too (tell me about yourself, etc).

You'll get a stack of 100 poker chips at the beginning of the day. In each interview, you'll be asked to make bets on your answers to brainteasers using your chips. Be careful in your bets... Good luck ending the day with nonzero chips!

Sep 4, 2012

Hello guys,

I know that there were many posts about Jane Street interviews (for a quantitative trading summer internship) and that they focus on mental math and probabilities.

But the fact is that I am a student in France and I don't know how to prepare it. I didn' t find interesting books ..

If anyone could help me ..

Thanks

Sep 4, 2012

The poker chip concept is so cool.

I hope they don't ask you stupid consulting type "estimate the gallons in the ocean" then bet on it type of questions. Would rather see straight prob. questions and then bet on that.

Hope they give you enough chips to make it statistically significant.

Sep 4, 2012
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Sep 17, 2018