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

With 3,500 employees, no banking license, no consulting fees, and no investment banking business, they rely solely on trading, achieving an annual revenue of $39.6 billion in 2025. This exceeds JPMorgan Chase, Goldman Sachs, and any other firm in Wall Street history.

With a profit margin of 65-70%, the company has a per capita profit of about $8 million to $9 million. Among companies with over 1,000 employees, it's the highest in the world. Next door, Citadel Securities has 1,800 employees with a per capita profit of $3.6 million; Hudson River Trading is only at $6.6 million; even Nvidia, a company funded by the entire world, has a per capita profit of only $2.9 million.

Therefore, this week, all financial practitioners on Twitter were discussing the same thing: How did Jane Street recruit all these people?

The Hardest Company to Enter on Wall Street

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

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

Many founders of funds and project parties in the cryptocurrency circle have intersections with Jane Street before switching careers to crypto, but the vast majority have "interviewed," not "received offers."

Zhu Su, founder of Three Arrows Capital, tweeted a memory: "I interviewed Jane Street in Tokyo and Hong Kong in December 2008. A friend of mine was in their Tokyo office, a PhD in architecture from the University of Tokyo who pivoted to quantitative trading. After the second round, I realized I should learn programming, instead of working with Excel."

The head of growth at 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 also chased the long-discussed puzzle lock question from Jane Street.

Many senior players in the cryptocurrency circle have brushed shoulders with this company at some point.

And the difficulty of Jane Street's company interviews is among the top on Wall Street. According to the grading of candidate interview difficulty by Twitter user @vivoplt, Jane Street ranks at the top of difficulty S+, alongside top AI labs.

A Twitter user named Hampton recalled his interview in 2012. It reads a bit like black humor: they met at an ATM next to Bank of America, beside the World Trade Center in the Financial District. Then the interviewer took him on the A line subway heading towards Central Park. They played chess on the subway without a board, solely verbally. Coin tossing decided whether to start with 1.e4 or 1.d4. If they hadn't determined the winner by the time they reached Columbus Circle at 59th Street, they would start blitzing until they reached Central Park. Hampton said he lost at the station in Times Square.

Another investor named Alex Song recalled his Jane Street interview in 2010: "The worst interview of my life. For an hour, the guy across from me explained the rules of a card game and gave me an hour to find the dominant winning strategy. This was definitely not the Putnam math competition level, but it was worse than D.E. Shaw, QVT, or DRW."

A Twitter user retweeting this added: this Alex later had an impressive resume: crushing Stanford undergrad, fixed-income trading at Morgan Stanley, fixed-income investment at Bain Capital, Harvard MBA, top hedge fund, early financial recruiting head at Ramp, but Jane Street did not hire him.

Some interviewees said: "To this day, this is still the hardest interview process in investment banking; you can prepare for other companies, but Jane Street is truly unprepared for." Some even joked: "If Oppenheimer were still alive, I would wager he still couldn't pass Jane Street's third-round interview."

Tricky Interview Questions

Just listening to stories isn't enough. Below are several questions that have been repeatedly discussed on Twitter. The editor selected a few of varying difficulties, and readers can try 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 country in the Middle East?"

Question 3: "A safe has a six-digit combination. The lock will tell us if we have correctly entered four digits or more, but only if all six are right will it truly open. What is the optimal strategy to find the combination with the least number of attempts?"

Question 4: "You have 30 actual ropes (not strings in code). Randomly tie together all 60 ends in pairs; how many rings do you expect will form? For example: tying both ends of one rope = 1 ring; repeating this for 30 ropes = 30 rings. Tying two ropes together = 1 big ring; tying 30 ropes together in pairs = 15 rings."

Question 5: "What is the next closest date after today with all non-repeating digits? Format DD/MM/YYYY. How sure are you?"

Question 6: "What integer is 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: "What is the angle in degrees between the hour hand and the minute hand at 3:15 PM?"

Question 10: "You have a chance to bid on a treasure chest. The true value of the chest is some number between $0 and $1,000, and you are 100% confident it falls within this range. If your bid is equal to or greater than the true value of the chest, you win it at your bid price; if it is lower, you get nothing. At the same time, 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 am going to roll a 20-sided die (numbers 1 to 20) once. How much would you be willing to pay to play this game where you receive an amount equal to the number shown on the die? Now, modify 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? How much is this game worth?"

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

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

Question 14: "Two equally matched teams play a best-of-seven series. What is the probability that the series will be decided in the 7th game?"

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

Question 16: "100 prisoners are locked in 100 separate cells. There is only one lightbulb 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 lightbulb room at random; the number of times and the order of entry are completely uncontrollable. Any prisoner may declare at any time: we 100 have all been into this room. If correct, all are freed; if wrong, all are executed. Before the game starts, the prisoners can discuss strategies, but cannot communicate afterward. What is the optimal strategy?"

Question 17: "Suppose I have 10 coins. One is a fair coin (50% heads/tails), and the other 9 are biased, but each coin's degree of bias is unknown. Given limited flipping chances, how can you identify the fair coin?"

Question 18: "1,000 ninjas are arranged in a circle, each holding 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 remains. What is the number of that person?"

If you passed all the previous phone interviews, the last hurdle 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 an hour, all facing off against current traders. In each round, you must use those chips to place bets or make markets. When SBF entered Super Day back then, he was told: "Anyone who loses all their chips has never gotten an offer."

What Kind of People Does Jane Street Look For?

Augustin Lebron is a former trader at Jane Street, who worked for many years in the London office and managed that cohort of interns, including SBF. After leaving Jane Street, he wrote a book called "The Laws of Trading," and in an interview, he said something very candid: "Globally, maybe only one or two thousand newcomers can enter truly good quantitative trading firms each year."

"I have talked with many students. If you ask them why they want to do this, they will say math is interesting, AI is interesting, statistics is interesting. But these skills can be applied in many other areas, so this reason alone doesn't hold up." However, Augustin Lebron believes the real answers are typically two: first, it is a high-status thing; second, they actually want to get rich.

So what kind of people does Jane Street actually recruit?

Augustin Lebron clearly stated in the interview that these firms look for raw talent, not knowledge. In other words, their past experiences trained them for this industry, such as people who have played poker, participated in sports betting, and have actually made money. People who have had experiences in life involving decision-making under uncertainty and bearing the economic consequences of those decisions.

Another very typical category of people is those who will leave quickly after joining, even if they are extremely smart, very good at math, and excellent at problem-solving, but they simply do not like trading. They care more about solving that math problem than making money. "In this line of work, you ultimately must make money."

Some old Jane Streeters have also summarized several common reasons candidates fail: excessive confidence; silent thinking, as Jane Street emphasizes thinking out loud extremely; refusal to bet, if given the chance to make a market but you refuse, it means "you are unwilling to take risks"; also, when you get into a bad position, the interviewer will intentionally give you a terrible quote, and if you panically accept, you've proven you shouldn't be hired. Ignoring hidden information in the questions, etc.

And perhaps these are the important reasons why Jane Street makes a staggering $40 billion in profits annually.

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