How Maven Securities's process runs, as candidates and the firm describe it, and the questions candidates report, each with a worked solution. Free, no sign-up.
Graduate Trader · Fourth round · Logic · reported by a candidate
You have a balance scale and some balls that look identical, except that one has a different weight.
(a) Eight balls, and the odd one is heavier. Fewest weighings to guarantee finding it?
Answer and worked solution
Answer: 2
Key idea. Each weighing has 3 outcomes, so k weighings distinguish at most 3k cases.
8 cases ≤ 3² = 9.
Weigh 3 v 3. Balanced: weigh the other 2. Unbalanced: take the heavy 3 and weigh 1 v 1.
2 weighings.
(b) Twelve balls, and you don't know whether the odd one is heavier or lighter. Fewest weighings to find it (and whether it's heavy or light)?
Answer and worked solution
Graduate Trader · Fourth round · Expected value · reported by a candidate
n people each get a name sticker for someone in the group, assigned at random (a random permutation). Start with one person, go to the person named on their sticker, and so on until you return: that's a cycle. Every person is in exactly one cycle.
For n = 4, what is the expected number of cycles?
Answer and worked solution
Answer: 25/12 ≈ 2.0833
Key idea. Build the permutation one person at a time: the k-th person closes a new cycle with probability 1/k.
E[cycles] = 1 + 1/2 + … + 1/n.
n = 4: 1 + ½ + ⅓ + ¼ = 25/12 ≈ 2.08.
Check. For large n, about ln n + 0.577.
Interviewers may push further: For large n, about how many? (ln n + 0.577.)
Trader · Interview · Behavioural · reported by a candidate
Behavioural questions candidates report:
Describe a difficult situation where things did not go as expected.
In the trading game, explain what you were thinking when you made that mistake.
Describe a time you achieved something your peers did not.
What do you do for fun?
Answer one out loud, as you would in the interview.
Model answer
Use a short story: the situation in one sentence, what you did (not the team), the result with a number if you have one, and what you'd do differently. Aim for about two minutes.
On the trading mistake: own it quickly, explain the reasoning at the time, say what you'd do now. Interviewers care more about how you review errors than about the error.