华尔街最难进的公司：年赚400亿的Jane Street，面试题有多变态？

This week, the most talked-about entity on Wall Street is Jane Street.

With 3,500 employees, no banking license, no consulting fees, and no investment banking business, it generated $39.6 billion in total revenue for fiscal year 2025 solely through trading. That surpasses JPMorgan Chase, surpasses Goldman Sachs, and surpasses any institution in Wall Street history.

Based on a 65-70% profit margin, this company's per-employee profit is approximately $8 million to $9 million. Among all companies with more than 1,000 employees, it ranks first globally. For comparison, neighboring Citadel Securities, with 1,800 employees, has a per-employee profit of $3.6 million; Hudson River Trading's is $6.6 million; and even Nvidia, a company seemingly effortlessly fed profits by the world, has a per-employee profit of only $2.9 million.

So this week, finance professionals across Twitter are all discussing the same thing: How did Jane Street manage to hire these people?

Wall Street's Toughest Company to Get Into

The name Jane Street is not unfamiliar in the crypto space.

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

Many crypto fund founders and project builders have some intersection with Jane Street on their resumes before transitioning to crypto, but the vast majority "interviewed" there, rather than "received an offer."

Three Arrows Capital founder Zhu Su also tweeted a memory: "Interviewed with Jane Street in Tokyo and Hong Kong in December 2008. My friend was then in their Tokyo office, a PhD in Architecture from the University of Tokyo who switched to quantitative trading. After the second round, I realized one thing: I should learn to code, not just mess with Excel."

The Head of Growth at the Monad Foundation retweeted a question he was asked during his sophomore year at MIT, saying he "still remembers how insane that interview was." Brian, co-founder of Glider Finance, also joined the discussion about a legendary Jane Street lock puzzle question that has been circulating for a long time.

Many seasoned players in the crypto space have had close encounters with this company at some point.

And the difficulty of Jane Street's interviews is among the highest on Wall Street. According to Twitter user @vivoplt's ranking of interview difficulty for candidates, Jane Street is at the very top of the S+ tier, on par with top AI labs.

One Twitter user, Hampton, shared a memory of his 2012 interview. It reads like dark comedy: Meet at Fulton Street in the Financial District, near the Bank of America ATM next to the World Trade Center. The interviewer then took him on the A train heading towards Central Park. They played chess on the subway. No board, entirely verbal. Flipping a coin decided the opening move was 1.e4 or 1.d4. If they hadn't decided the winner by Columbus Circle (59th Street), they'd switch to blitz chess until Central Park. Hampton said he lost at Times Square station.

Another investor named Alex Song recalled his Jane Street interview in 2010: "The worst interview of my life. One hour, this guy explained the rules of some card game to me, gave me an hour to find the dominant winning strategy. It's absolutely nothing like the Putnam math competition, but way worse than D.E. Shaw, QVT, DRW."

Another Twitter user replying to this thread added: This Alex later had a stellar resume: Stanford undergrad, fixed income trading at Morgan Stanley, fixed income investing at Bain Capital, Harvard MBA, top hedge fund, early financial hiring lead at Ramp. Jane Street didn't hire him.

Some interviewees say: "This is still the toughest interview process in investment banking. You can prepare for other companies, but you really can't prepare for Jane Street." One netizen even joked: "Even if Oppenheimer were alive today, I bet he still wouldn't pass Jane Street's third round of interviews."

Difficult Interview Questions

Hearing stories isn't enough. Below are some questions frequently discussed on Twitter. The BlockBeats editor picked a few of varying difficulty for readers to try themselves and see how many you can solve.

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

Question 2: "Estimate how many Marines it would take to overthrow a major country in the Middle East."

Question 3: "A safe has a six-digit code. The lock will tell us if we have entered four or more digits correctly, but only the full six digits will open it. What is the optimal strategy to find the code with the fewest attempts?"

Question 4: "You have 30 physical ropes (not strings in code). You randomly pair up and tie all 60 ends. What is the expected number of loops formed? Example: Tying both ends of one rope together = 1 loop. Doing this for all 30 ropes = 30 loops. Tying the ends of two ropes to each other = 1 big loop. Pairing all 30 ropes this way = 15 loops."

Question 5: "What is the next date after today where all the digits 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 statement is true?"

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

Question 9: "What is the angle between the hour hand and the minute hand on a clock at 3:15 PM?"

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

Question 11: "I roll a 20-sided die (numbers 1 to 20) once. How much would you pay to play this game once, where you receive an amount in dollars equal to the number rolled? Now change the rule: Each round, you can either 'take the current number rolled' or 'roll again'. You have 100 rounds total. What is your optimal strategy? What is the value of this game?"

Question 12: "On a blackboard, 100 sentences are written. Sentence 1 says: 'At most 0 of these 100 sentences are true.' Sentence 2 says: 'At most 1 of these 100 sentences is true.' ... Sentence n says: 'At most n−1 of these 100 sentences is true.' Sentence 100 says: 'At most 99 of these 100 sentences is true.' How many of these 100 sentences are actually true?"

Question 13: "I flip 4 coins. What is the expected number of heads? Now you are given one chance to re-flip all 4 coins (you must accept the new result). What is the expected value now?"

Question 14: "Two perfectly equal teams play a best-of-seven series. What is the probability that the series goes to Game 7 to determine the winner?"

Question 15: "Suppose you and your roommate host a party and invite 10 other roommate pairs. During the party, you ask everyone except yourself: 'How many hands did you shake?' It is known that no one shook hands with their own roommate. Everyone gives you a different answer. How many hands did your roommate shake?"

Question 16: "100 prisoners are in 100 separate cells. There is only one light bulb room. Only one prisoner can enter at a time, and they can turn the light on or off. Prisoners are called into the room randomly, with no control over the order or frequency. Any prisoner can announce at any time: 'All 100 of us have been in this room.' If correct, everyone is freed; if wrong, everyone is executed. Prisoners can devise a strategy before the game starts but cannot communicate afterwards. What is the optimal strategy?"

Question 17: "Suppose I have 10 coins. One is a fair coin (50% heads, 50% tails), and the other 9 are biased, but the degree of bias for each is unknown. With a limited number of flips, how do you identify the fair coin?"

Question 18: "1000 ninjas stand in a circle, each with a knife. Ninja 1 kills Ninja 2, Ninja 3 kills Ninja 4, Ninja 5 kills Ninja 6, and so on, continuing around the circle until only one person remains. What is the number of that person?"

If you survive all the preceding phone interviews, the final round is called Super Day. Upon entering, a staff member hands you 100 poker chips. Then follows 4 to 6 back-to-back one-hour technical interviews, each one pitting you against a current trader. In each round, you use these chips to bet or make markets. When SBF entered Super Day, he was told: "No one who lost all their chips has ever received an offer."

Who Does Jane Street Want?

Augustin Lebron, a former trader at Jane Street who worked in the London office for many years and managed the intern program that included SBF, wrote a book after leaving called 'The Laws of Trading'. In an interview, he said something very candid: "Globally, each year there are probably only one or two thousand newcomers who can enter truly good quantitative trading firms."

"I've talked to many 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 this reason alone doesn't really hold up." However, Augustin Lebron believes the real answers are usually two: first, it's a high-status thing; second, they actually want to get rich.

So what kind of people does Jane Street actually hire?

Augustin Lebron explicitly stated in the interview that these institutions look for raw talent, not knowledge. That is, their past has pre-trained them for this line of work, such as people who have played poker, engaged in sports betting, and actually made money. People who have had life experiences of "making decisions under uncertainty and bearing the economic consequences of those decisions."

Another very typical type is people who get weeded out quickly, even if they are extremely smart, very good at math, and very good at solving problems. They just don't like trading. They care more about solving the math problem than making money. "In this business, you ultimately have to make money."

Some veteran Jane Streeters have also summarized a few common reasons candidates get rejected: overconfidence; silent thinking (Jane Street heavily emphasizes thinking out loud, quiet thinking is a big no-no); refusing to bet (if given a chance to make a market and you refuse, it means "you are unwilling to take risks"); additionally, when you are in a bad position, the interviewer will deliberately give you a terrible quote. If you accept it in a panic, you've proven you shouldn't be hired. Ignoring hidden information in the problem, etc.

And these are perhaps the important reasons why Jane Street earns $40 billion a year.