Even if Oppenheimer lived to today, he might not be able to answer Jane Street's third round interview questions.

This week, the most discussed topic on Wall Street is Jane Street.

Written by: Rhythm

With 3,500 employees, no banking license, no consulting fees, and no investment banking operations. Solely relying on trading, the full year revenue for 2025 is $39.6 billion. More than JPMorgan. More than Goldman Sachs. More than any institution in Wall Street's history.

Calculating a profit margin of 65-70%, the average profit per employee in this company is about $8 million to $9 million. Among companies with more than 1,000 employees, it ranks first in the world. Next door, Citadel Securities has 1,800 people, with an average profit of $3.6 million; Hudson River Trading only has $6.6 million; even Nvidia, a company being chased globally for investment, has an average profit of only $2.9 million.

Thus, this week, the entire financial community on Twitter is discussing the same thing: How did Jane Street manage to bring this group of people on board?

The Hardest Company to Enter on Wall Street

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

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

Many founders of funds and projects in the crypto circle had interactions with Jane Street before transitioning into crypto, but the vast majority "interviewed" rather than "received offers."

The founder of Three Arrows Capital, Zhu Su, also tweeted to recall: "In December 2008, I interviewed with Jane Street in Tokyo and Hong Kong. A friend of mine was at their Tokyo office, a PhD in architecture from the University of Tokyo who transitioned to quant. After the second round of interviews, I realized something: I should learn programming, not work on Excel."

The Growth Director of the Monad Foundation retweeted a question he was asked during his sophomore year at MIT, saying, "I still remember how crazy that interview was." Glider Finance co-founder Brian is also discussing the long-circulated password lock question from Jane Street.

Many senior players in the crypto circle have brushed past this company at some point.

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

A Twitter user named Hampton recalls his interview in 2012. It reads a bit like black humor: they met around Fulton Street in the financial district, next to the Bank of America ATM by the World Trade Center. Then the interviewer took him on the A train subway towards Central Park. She and the interviewer played chess on the subway, but without a chessboard, just verbally. They flipped a coin to decide whether to open with 1.e4 or 1.d4. If by 59th Street Columbus Circle they hadn't come to a conclusion, they would start blitzing, continuing until reaching Central Park. Hampton said he lost at the Times Square stop.

Another investor named Alex Song recalls his Jane Street interview in 2010: "The worst interview of my life. An hour, the guy across from me explained the rules of some card game, giving me an hour to figure out the dominant winning strategy. This was definitely not like a Putnam math competition, but worse than D.E. Shaw, QVT, and DRW."

A Twitter user who retweeted this commented: this Alex later had an impressive resume with Stanford undergraduate, Morgan Stanley fixed income trading, Bain Capital fixed income investing, Harvard MBA, top hedge fund, and early financial recruitment lead at Ramp, but Jane Street did not hire him.

Some interviewees stated: "This is still the hardest interview process in investment banking. At other companies, you can prepare, but you truly cannot prepare for Jane Street." Some users joked: "If Oppenheimer were still alive now, I'd bet he still couldn't pass Jane Street's third round interview."

Tricky Interview Questions

Just hearing the stories isn't enough. Below are several questions that have been repeatedly discussed on Twitter. The editors picked a few with varying difficulties, and readers can also try to see how many they can answer.

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 country in the Middle East?"

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

Question 4: "You have 30 real ropes (not string in code). Tie all 60 ends randomly in pairs; how many rings do you expect will form? For example: tying both ends of one rope = 1 ring; doing this for 30 ropes = 30 rings. Tying two ropes' ends together = 1 large ring; tying 30 ropes together in pairs = 15 rings."

Question 5: "What is the next closest date with all unique digits after today? 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 composed only of the digits 1 and 0 that is divisible by 15?"

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

Question 10: "You have a chance to bid on a treasure chest. The chest's actual value is some number between $0 and $1,000, and you are 100% confident it is in this range. If your bid equals or exceeds the actual value, you win the chest at your bid; if it's lower, you get nothing. Also, you have a friend willing to buy the chest from you for 1.5 times its actual value. What should you bid?"

Question 11: "I am rolling a 20-sided die (numbers 1 to 20). How much would you be willing to pay to play this game, where you get an amount based on the number rolled? Now change the rules: in each round, you can choose to 'take the current number on the die' or 'roll again.' A total of 100 rounds. What is your optimal strategy? What is this game worth?"

Question 12: "There are 100 statements written on the board. The 1st statement says, 'At most 0 of these statements are true.' The 2nd statement says, 'At most 1 of these statements is true' … The nth statement says, 'At most n-1 of these statements are true.' The 100th statement says, 'At most 99 of these statements are true.' How many of these statements are truly true?"

Question 13: "I flip 4 coins, what is the expected number of heads? Now, you get a chance to flip all 4 coins again (must accept the new result), what is the expected value now?"

Question 14: "Two teams of equal strength play a best-of-seven series. What is the probability that the series will reach a game 7?"

Question 15: "Suppose you and a roommate co-host a party, inviting 10 other pairs of roommates. During the party, you ask everyone except yourself: how many people have you shaken hands with? Given that no one has shaken hands with their roommate; and every answer is different. How many times did your roommate shake hands?"

Question 16: "100 prisoners are confined in 100 separate cells. There is only one light bulb room in the prison, and only one prisoner is allowed in at a time to turn the light on or off. Prisoners are called into the light bulb room randomly, and the order is completely uncontrollable. Any prisoner can declare at any time: 'All 100 of us have been in this room.' If correct, everyone is released; if wrong, everyone is executed. Before the game starts, prisoners can discuss strategies, but cannot communicate afterward. What is the optimal strategy?"

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

Question 18: "1,000 ninjas stand in a circle, each with a knife. Ninja number 1 kills ninja number 2, ninja number 3 kills ninja number 4, ninja number 5 kills ninja number 6, and so on, continuously around the circle until only one person remains. Which ninja is the last survivor?"

If you survive all the preceding phone interviews, the final round is called Super Day. Upon entering, the staff will hand you 100 poker chips. Next, there will be a series of 4 to 6 technical interviews, each lasting one hour, all against current traders. In each session, you must use these chips to place bets or provide liquidity. When SBF entered Super Day, he was told: "No one who lost all their chips has ever received an offer."

What Kind of People Does Jane Street Want?

Augustin Lebron is a former trader at Jane Street, who worked in the London office for many years and managed the intern program that included SBF. After leaving Jane Street, he wrote a book titled "The Laws of Trading," and in an interview, he expressed a very honest opinion: "Globally, only about one or two thousand newcomers can get into truly good quantitative trading firms each year."

"I have spoken to many students. If you ask them: why do you want to do this, they will say math is interesting, AI is interesting, statistics are interesting. But these skills can be applied in many other areas, so that reason alone does not hold up." However, Augustin Lebron believes the real answer is usually twofold: first, it is a high-status pursuit; second, they actually want to get rich.

So what kind of people does Jane Street actually hire?

Augustin Lebron clearly states in the interview that these institutions recruit based on raw talent, not knowledge. This means that their past experiences have pre-trained them for this field, such as those who have played poker, engaged in sports betting, and actually made money. They are individuals who have experienced "making decisions under uncertainty and bearing economic consequences for those decisions" at some point in their life.

Another very typical group is those who will quickly exit after joining, even if these individuals are extremely smart, very good at math, and skilled at problem-solving. They simply do not enjoy trading. They care more about solving that math problem than making money. "In this line of work, you have to make money in the end."

Some veteran Jane Streeters have summarized several common reasons candidates fail: excessive confidence; silent thinking; Jane Street emphasizes thinking out loud, while quiet contemplation is a huge taboo; refusing to place a bet, if you decline an opportunity to provide liquidity, it’s equivalent to "you are unwilling to take risks"; additionally, when you find yourself in a poor position, the interviewer will deliberately provide you a very bad quote, and if you panic and accept, you prove that you should not have been hired. Ignoring hidden information in the questions, and so on.

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