Jane Street Interview Questions
Practice 53 real Jane Street interview questions for 2026 — Jane Street interview questions and interview preparation built from real problems used in actual interviews with detailed solutions. This collection emphasizes coding-first assessment, trading-flavored probability and puzzle questions, and ML/statistics tasks that mirror the firm’s focus on precision, speed, and clear reasoning. Expect short, whiteboard-style problem solving and paired coding that tests correctness, edge-case thinking, and clear verbalization of tradeoffs; prepare by sharpening algorithmic coding, probability modeling, time-series intuition, and concise system designs. Software engineering content dominates: problems repeatedly ask you to transform sparse time-stamped streams into dense rows, validate and canonicalize order-book/trade data across databases, and design low-latency message flows between exchanges and trading systems, plus implementation puzzles (e.g., Connect Four) and probability/game-theory questions. Data scientist questions cluster around real-vs-fake DNA classifiers, probability and queueing puzzles, and trading RFQ competitiveness analysis. Machine learning engineering questions focus on end-to-end training frameworks, time-series forecasting for trading, and small runtime/compiler design for domain-specific languages.
"I got asked a hardcore MCM DP question and I saw it on PracHub as well. Solved that question in 5 minutes. Without PracHub I doubt I could solve it in 5 hours. Though somehow didn't get hired, perhaps I guess I solved it too fast? /s"
"Believe me i'm a student here jn US. Recently interviewed for MSFT. They asked me exact question from PracHub. I saw it the night before and ignored it cause why waste time on random sites. I legit wanna go back and redo this whole thing if I had chance. Not saying will work for everyone but there is certainly some merit to that website. And i'm gonna use it in future prep from now on like lc tagged"
"10 years of experience but never worked at a top company. PracHub's senior-level questions helped me break into FAANG at 35. Age is just a number."
"I was skeptical about the 'real questions' claim, so I put it to the test. I searched for the exact question I got grilled on at my last Meta onsite... and it was right there. Word for word."
"Got a Google recruiter call on Monday, interview on Friday. Crammed PracHub for 4 days. Passed every round. This platform is a miracle worker."
"I've used LC, Glassdoor, and random Discords. Nothing comes close to the accuracy here. The questions are actually current — that's what got me. Felt like I had a cheat sheet during the interview."
"The solution quality is insane. It covers approach, edge cases, time complexity, follow-ups. Nothing else comes close."
"Legit the only resource you need. TC went from 180k -> 350k. Just memorize the top 50 for your target company and you're golden."
"PracHub Premium for one month cost me the price of two coffees a week. It landed me a $280K+ starting offer."
"Literally just signed a $600k offer. I only had 2 weeks to prep, so I focused entirely on the company-tagged lists here. If you're targeting L5+, don't overthink it."
"Coaches and bootcamp prep courses cost around $200-300 but PracHub Premium is actually less than a Netflix subscription. And it landed me a $178K offer."
"I honestly don't know how you guys gather so many real interview questions. It's almost scary. I walked into my Amazon loop and recognized 3 out of 4 problems from your database."
"Discovered PracHub 10 days before my interview. By day 5, I stopped being nervous. By interview day, I was actually excited to show what I knew."
"I recently cleared Uber interviews (strong hire in the design round) and all the questions were present in prachub."
"The search is what sold me. I typed in a really niche DP problem I got asked last year and it actually came up, full breakdown and everything. These guys are clearly updating it constantly."
Four Fair Coins: Expected Payoff and Pricing Two Magic Wands
You play the following game: four fair coins are tossed at the same time. For every coin that lands heads, you are paid \$1. The interviewer walks you...
Build a Web Calculator That Matches a Reference App
You are in a 45–60 minute phone screen (with screen sharing) for a Fullstack/Frontend role. The interviewer shares a link to a simple calculator web a...
Sealed-Bid Auction for a Box of 200 Coin Flips (and an Informed Opponent)
You are one of two bidders in a sealed-bid auction for a box. The box's payout is determined by flipping 200 fair coins: it pays \$1 for every coin th...
Calculate dice game win probability
Calculate dice game win probability Dice Game With Tie Rerolls: Probability You Eventually Win Context - Three players each roll a fair standard 6-sid...
Bounds on the Probability of Rain on at Least One Weekend Day
The probability that it rains on Saturday is $p$, and the probability that it rains on Sunday is $q$. Nothing is said about whether the two days are i...
Analyze trading RFQ competitiveness data
This question evaluates a candidate's skills in exploratory data analysis, Excel-based feature engineering, basic statistical modeling, and interpreta...
Which Dice Game Wins More Often: One Six in 4 Rolls, or Double Sixes in 24 Rolls?
You are offered two dice games and asked to decide which one gives you a better chance of winning. - Game 1: Roll one fair six-sided die 4 times. You ...
Five Pumpkins Weighed in Every Pair: Find the Total Weight
You have 5 pumpkins. You weigh them two at a time, in every possible pairing, and the scale readings for the ten pairs are: $$21,\ 22,\ 23,\ 24,\ 25,\...
Pick a Number 1-100 Where the Higher Pick Pays a 10-Point Penalty: Optimal Strategy
Two players simultaneously each pick an integer from 1 to 100 (inclusive). The winner is decided as follows: take the larger of the two picks, subtrac...
Coin-Flip Race to Four: Game Length and a Conditional Win Probability
Two players play a coin-flipping game with a single fair coin. The coin is flipped once per round. Every heads counts for Player 1, and every tails co...
Sort trade executions into a canonical order
You are building a small component in a trading system that consumes trade execution records from an upstream feed. The records may arrive out of orde...
Dice Duel: 30-Sided Die vs. 20-Sided Die with One Blind Reroll
Alice and Bob play a dice game. Alice has a fair 30-sided die (faces $1$ through $30$) and Bob has a fair 20-sided die (faces $1$ through $20$). Each ...
Optimize trade PnL table updates
This question evaluates understanding of incremental aggregation and state management, including handling overlapping predicates, caching expensive or...
Minimum Common Pairwise Correlation Among Seven Identically Distributed Random Variables
Suppose $X_1, X_2, \ldots, X_7$ are seven random variables defined on the same probability space. Each has mean $0$ and variance $1$, and they are ide...
Bottom-Insertion Connect Game: Detect the First k-in-a-Row Winner
Two players, B and R, take turns dropping pieces onto a board that covers the upper half-plane of an integer grid. Columns are indexed by arbitrary in...
Marketplace Data Store: Order Matching and End-of-Day Reconciliation
Marketplace Data Store: Order Matching and End-of-Day Reconciliation You are building the core of a marketplace where sellers list individual units of...
Pricing a Mystery Money Box: Expected Value, Adverse Selection, and Competition
A company manufactures sealed boxes. Each box contains a cash amount that is an integer number of dollars drawn uniformly at random from $1$ to $100$ ...
Implement Connect Four with bottom push-up
Implement a Connect Four variant with bottom push-up. In standard Connect Four a dropped disc falls to the lowest empty cell of a column. In this vari...
Board Simulation: Bottom-Insert Pieces with Uniform Row and Column Detection
Board Simulation: Bottom-Insert Pieces with Uniform Row and Column Detection You must simulate a 2-D game board with R rows and C columns. Each cell i...
Solve queue switch and coin change puzzles
This entry contains two separate interview-style quantitative/algorithmic questions. --- 1. Queue switching decision problem You are standing in a sin...