Author: Rhythm

Jane Street was the most talked-about topic on Wall Street this week.

With 3,500 employees, no banking license, no consulting fees, and no investment banking business, it aims to generate $39.6 billion in revenue by 2025 solely through trading. This surpasses JPMorgan Chase, Goldman Sachs, and any institution in Wall Street history.

Based on a profit margin of 65-70%, this company's profit per employee is approximately $8 to $9 million. Among all companies with more than 1,000 employees, this is the highest globally. Citadel Securities next door, with 1,800 employees, has a profit per employee of $3.6 million; Hudson River Trading only has $6.6 million; even Nvidia, a company that receives massive funding worldwide, only has a profit per employee of $2.9 million.

So this week, finance professionals across Twitter have been discussing the same thing: how did Jane Street manage to recruit these people?

The hardest company to get into on Wall Street

The name Jane Street is not unfamiliar in the cryptocurrency world.

FTX founder SBF's first job was as an intern at Jane Street. SBF's ex-girlfriend, Caroline Ellison, who later became the CEO of Alameda and left a mess behind, also came from there. SBF later repeatedly mentioned in Michael Lewis's book that the market thinking framework he learned at Jane Street almost determined all his trading intuitions for FTX and Alameda.

Many fund founders and project teams in the crypto world have connections with Jane Street on their resumes before switching to crypto, but for the vast majority of them, it was "interviews" rather than "receiving offers".

Zhu Su, founder of Three Arrows Capital, also tweeted his recollection: "I interviewed Jane Street in Tokyo and Hong Kong in December 2008. My friend was working at their Tokyo office at the time; he had a PhD in architecture from the University of Tokyo who had switched to quantitative analysis. After the second round of interviews, I realized something: I should learn programming instead of working with Excel."

The head of growth at the Monad Foundation retweeted a question he was asked during his sophomore year at MIT, saying, "I still remember how crazy that interview was." Brian, co-founder of Glider Finance, is also discussing the same long-standing combination lock question posed by Jane Street.

Many veteran players in the crypto community have missed out on this company at some point in their lives.

Jane Street's interview difficulty is among the highest on Wall Street. According to a ranking of candidate interview difficulty by Twitter user @vivoplt, Jane Street is at the very top of the S+ difficulty level, on par with top AI labs.

A Twitter user, Hampton, recounts her 2012 job interview. It reads somewhat like dark humor: They agreed to meet on Fulton Street in the Financial District, next to an ATM near the World Trade Center. The interviewer then led her onto the A train heading towards Central Park. She and the interviewer played chess on the subway. However, there was no chessboard; everything was dictated. A coin toss determined whether the opening was 1.e4 or 1.d4. If the game wasn't decided by Columbus Circle on 59th Street, they started a blitzkrieg, continuing all the way to Central Park. Hampton says she lost at the Times Square stop.

Another investor, Alex Song, recalled his Jane Street interview in 2010: "The worst interview of my life. One hour, the guy across from me was explaining the rules of some card game, and I had one hour to figure out the dominant winning strategy. It was definitely not a Putnam math competition or anything like that, but it was worse than DE Shaw, QVT, and DRW."

Another Twitter user who retweeted this added insult to injury: This Alex later had a resume that included a crushing Stanford undergraduate degree, fixed income trading at Morgan Stanley, fixed income investment at Bain Capital, a Harvard MBA, a top hedge fund, and the head of early-stage financial recruitment at Ramp, yet Jane Street didn't hire him.

One interviewee said, "This is still the most difficult interview process in investment banking. You can prepare for other companies, but you really can't prepare for Jane Street." Some netizens even joked, "If Oppenheimer were still alive, I bet he still wouldn't pass the third round of interviews at Jane Street."

tricky interview questions

Just hearing the stories isn't enough. Below are some questions that have been repeatedly discussed on Twitter. The editor has selected a few with varying levels of difficulty, and readers can try them out themselves to see how many they can solve.

Question 1: "Estimate how many windows there are in New York City. Explain your methodology."

Question 2: "How many Marines do you estimate would be needed to overthrow a major Middle Eastern power?"

Question 3: "A safe has a six-digit combination. The lock will prompt you if you have entered four or more digits correctly, but it will only open if all six digits are correct. What is the optimal strategy to find the combination with the fewest attempts?"

Question 4: "You have 30 real ropes (not strings in code). Tie all 60 ends together randomly in pairs. How many loops do you expect to form? For example: tying both ends of one rope together = 1 loop; 30 ropes tied together in this way = 30 loops. Tying the ends of two ropes together = 1 large loop; 30 ropes tied together in pairs = 15 loops."

Question 5: "What is the next nearest date after today where all numbers are unique? Format: DD/MM/YYYY. How confident are you?"

Question 6: "What is the integer closest to the square root of 1420?"

Question 7: "I have a relative who is a professional baseball player. What is the probability that this fact is true?"

Question 8: "What is the smallest positive integer that consists only of 1s and 0s and is divisible by 15?"

Question 9: "At 3:15 PM, what is the angle between the hour and minute hands of a clock?"

Question 10: "You have the opportunity to bid on a treasure chest. The chest's true value is somewhere between $0 and $1000, and you are 100% confident it falls within that range. If your bid is equal to or higher than the chest's true value, you win the chest; if it's lower, you get nothing. Meanwhile, a friend is willing to buy the chest from you for 1.5 times its true value. What should you bid?"

Question 11: "I'm rolling a 20-sided die (numbers 1 to 20). How much would you pay to play this game once, and how much money would you get equal to the number on the die? Now, let's change the rules: Each round you can choose to 'take the current number on the die' or 'roll again.' There are 100 rounds in total. What is your optimal strategy? How much is this game worth?"

Problem Twelve: "There are 100 statements written on the blackboard. The first statement says, 'At most 0 of these 100 statements are true.' The second statement says, 'At most 1 of these 100 statements is true,' and so on, until the nth statement says, 'At most n-1 of these 100 statements are true.' The 100th statement says, 'At most 99 of these 100 statements are true.' How many of these 100 statements are true?"

Problem Thirteen: "If I toss 4 coins, what is the expected number of heads? Now you have one chance to toss all 4 coins again (you must accept the new result), what is the expected number now?"

Question 14: "What is the probability that a best-of-seven series will go to a seventh game between two equally matched teams?"

Question 15: "Suppose you and one of your roommates are hosting a party and inviting 10 other pairs of roommates. During the party, you ask everyone except yourself: How many people have you shaken hands with? It's known that no one has shaken hands with their roommate; and everyone gives a different answer. How many hands did your roommate shake hands with?"

Problem 16: "100 prisoners are locked in 100 individual cells. There is only one light bulb room in the prison, and only one prisoner is allowed to enter at a time to turn the light on or off. Prisoners are randomly called into the light bulb room, and the number of times and the order in which they enter are completely unpredictable. Any prisoner can announce at any time: 'All 100 of us have been in this room.' If correct, everyone is released; if incorrect, everyone is executed. Before the game starts, the prisoners can discuss strategies, but they cannot communicate after the game begins. What is the optimal strategy?"

Problem 17: "Suppose I have 10 coins. One of them is a fair coin (50% heads and 50% tails), and the other nine are all unfair, but the degree of unfairness of each coin is unknown. Given a finite number of tosses, how do you find the fair coin?"

Question 18: "1000 ninjas stand in a circle, each holding a sword. Number 1 kills Number 2, Number 3 kills Number 4, Number 5 kills Number 6, and so on, continuing along the circle until only one ninja remains. What is that ninja's number?"

If you survive all the phone interviews, the final stage is called Super Day. Upon entering, staff will hand you 100 poker chips. This is followed by four to six consecutive one-hour technical interviews, all against active traders. In each interview, you'll use those chips to bet or make market-making decisions. When SBF entered Super Day, he was told, "No one who loses all their chips has ever received an offer."

What kind of people does Jane Street want?

Augustin Lebron, a former trader at Jane Street, worked for many years in the London office and managed the internship program that included SBF. After leaving Jane Street, he wrote a book called "The Laws of Trading," in which he made a very candid statement in an interview: "Globally, probably only one or two thousand new people get into truly good quantitative trading firms each year."

"I've talked to a lot of students. If you ask them why they want to do this, they'll say math is interesting, AI is interesting, statistics is interesting. But these skills can be used in many other places, so that reason alone doesn't really hold water." But Augustin Lebron believes the real answers are usually two: first, it's a high-status job; second, they actually want to make money.

So what kind of people did Jane Street actually hire?

In the interview, Augustin Lebron explicitly stated that these organizations hire based on raw talent, not existing knowledge. In other words, they want people who have prior experience in the field, such as those who have played poker, worked in sports betting, and actually made money from it. They want individuals who have already experienced making decisions under uncertainty and bearing the economic consequences of those decisions.

Another typical type of person enters the market and quickly exits, even if they are extremely intelligent, exceptionally good at math and problem-solving, but they simply don't like trading. They care more about solving the math problem than about making money. "In trading, you ultimately have to make money."

Some veteran Jane Street interviewers have summarized several common reasons why candidates are rejected: overconfidence; silent thinking (Jane Street highly emphasizes "think out loud," and quiet thinking is a major taboo); refusing to place bets (being given an opportunity to market make but refusing it is equivalent to "not being willing to take risks"); additionally, when you are in a bad position, the interviewer will deliberately give you extremely poor quotes, and if you panic and accept them, you prove that you should not have been hired; ignoring hidden information in the questions, etc.

And these factors may be the key reasons why Jane Street earns a staggering $40 billion a year.