Back in the day, JPM derivatives desk was known as being the most aggressive of the bulge banks(it still had the legacy team of Bill Winters tenure at the time). Certainly, for challenging interviews it blew all the other banks I looked at (GS, Deutsche, Merrill, Morgan) out of the water.
This was the main reason I accepted JPM in the end: I
knew the guys on the desk thought in really interesting ways.
Apart from the usual 'how many table tennis balls can you fit in the
London Underground network? How many Jelly Babies can you fit in a
jumbo jet? How many sheets of A4 paper can you fit in this room? How
many golf balls are there in mid flight at any given second of the
day? If I have a dice, and pay 1 for a 1, 2 for a 2... how much
would you pay to role the dice?' there were a couple of corkers at
JPM, the most memorable one of which was my final question, detailed
HR knocked on the door to remind the interviewer that the time slot was finished, so he said:
INTERVIEWER: "OK, one final question before you go - there is a deck
of cards in a pitch black room. Of the pack, 42 are face down, whilst 10 are face-up. How do you sort the cards into two separate piles, so that in each pile there are exactly 5 face-up?"
ME: "I would shuffle the cards again and again and again, so that any
bias in the original pack set-up was removed, and the positioning of
the cards should revert to unbiased probability. I would then split
the 52 cards into two equal packs of 26, so that the odds revert to
probability, giving the best chance of 5 up in each pack."
INTERVIEWER: "This isn't a probability question"
ME: "OK, well if it isn't a probability question, it is a logical
thinking question. The cards must feel different on each side so they can be identified by touch, or I must be able to switch the light on, or my eyes will slowly adjust to the darkness so I can see at least a bit, or even I can take the cards out of the room and split them outside in the light"
INTERVIEWER: "Stop being a smart a**e. The cards are identical, you
can't turn the light on, the door is locked, and it is absolutely
pitch black. You can't see anything now, nor will you ever be able
ME: "OK, I'm going to repeat the question back to you as I heard it,
just to clarify I haven't missed or misinterpreted any detail" [WHICH
I DULY DID, WORD FOR WORD, EXACTLY THE SAME AS HIS ORIGINAL QUESTION
INTERVIEWER: "You've got the question exactly right, it's just the
answer you got wrong"
ME: "Well in that case, I think you've given me an unanswerable trick question"
INTERVIEWER: [SAYING, WHILST STANDING UP TO SHAKE HANDS AND EXIT THE
ROOM}: "It's not a trick question. So I'll leave you to figure out
why you've got it wrong on your train journey home. Thanks for
I left, completely perplexed, and got the train back to uni, thinking
about it the whole way, and thinking that I'd somehow blown my interview on this one final question. The next day I got a call from
HR, offering me the job. When I turned up to work there a few months
later, I asked the guy who had interviewed me what the answer was.
His answer: "Oh, there isn't an answer. I just thought it would be
fun to mess with your head. You'd got all the other questions right
which I threw at you, and I couldn't have you going back to uni
thinking you were smarter than JPM now, could I?!"
Who says banks aren't evil!