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Report · Mid-2026

The Mid-2026 Quant Interview Report

What candidates preparing for Jane Street, Citadel, Optiver, SIG and the rest actually practice: the topics they drill, the firms they target, and the questions that trip them up. Every figure below comes from answers submitted on LeetQuant.

Covers 2026 through October

59%
of submitted answers are correct

Key findings

  • Probability is 41% of all practice, more than the next two topics combined.
  • Hard problems are 7% of solves, and only 47% of answers to them are correct, against 67% on easy ones.
  • Two Eggs, 100 Floors is the toughest well-attempted problem: just 31% of submitted answers are right.
  • Coin Toss — Two Heads is the most-solved problem on LeetQuant.

What candidates practice

Share of all solved problems by topic. Probability and brain teasers are the backbone of first-round screens at trading firms, and the practice mix reflects it.

  1. Probability41%
  2. Brain Teasers20%
  3. Calculus & Linear Algebra12%
  4. Statistics7%
  5. Stochastic Processes6%
  6. Market Making & Games4%
  7. Algorithms & Numerical4%
  8. Finance2%
  9. Options & Greeks2%
  10. Portfolio & Risk1%

Which firms they prepare for

Share of solves on problems reported at each firm. A problem can be tagged with several firms, so the shares add up to more than 100%.

  1. Goldman Sachs39%
  2. Jane Street30%
  3. Optiver22%
  4. Two Sigma19%
  5. Morgan Stanley18%
  6. Citadel15%
  7. IMC Trading11%
  8. Google10%

Difficulty and accuracy

How practice splits across difficulty, and what share of submitted answers are correct at each level.

LevelShare of solvesCorrect answers
Easy
46%
67%
Medium
47%
55%
Hard
7%
47%

The canon: most-solved problems

The problems solved most often on LeetQuant. If you are short on time, start here.

  1. 1Coin Toss — Two HeadsEasy
  2. 2Monty HallEasy
  3. 3Two ChildrenEasy
  4. 4Flips Until First HeadEasy
  5. 5Birthday ProblemMedium
  6. 6Expected Rolls for a SixEasy
  7. 7Bayes — Disease TestMedium
  8. 8Roll Until All Six FacesMedium
  9. 9Drunk PassengerMedium
  10. 10Trailing Zeros in 100!Easy

The questions that trip people up

Lowest share of correct answers among problems with enough attempts for a stable rate. These are worth a second pass even after you have seen the solution.

  1. Two Eggs, 100 Floors31% correct
  2. Poisoned Wine35% correct
  3. Roll Until All Six Faces41% correct
  4. Expected Max of Two Dice41% correct
  5. Horse Race — Top 342% correct
  6. Broken Stick Triangle43% correct

Methodology

Figures aggregate every answer submitted on LeetQuant in 2026 through October. No individual's data is shown.

A solve is a problem a candidate marked solved: by submitting a correct answer, by rating it themselves after reading the solution, or, for problems hosted on LeetCode, by marking them done. Correct answers is correct submissions divided by all submissions on problems with an answer to check; on self-graded problems, every easy / medium / hard rating counts as correct, except “Again” on the older four-button scale.

Firm tags come from public interview reports attached to each problem, not from where candidates work or applied. The hardest-problems list only includes problems with enough attempts for a stable rate.

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