Susquehanna Compared With Jane Street on Interview Style

SIG tests probability defended out loud while Jane Street tests live market making, and each interview style previews a different daily job.

Susquehanna International Group (SIG) and Jane Street are both options heavy proprietary trading firms with reputations for rigorous quantitative interviews, but the style of the interviews reflects a real difference in how each firm trains and promotes traders. SIG's process leans on probability and game theory puzzles solved out loud with an interviewer, testing how a candidate reasons under uncertainty in conversation, while Jane Street's process blends mental math, probability, and open ended trading games that reward a candidate who can adjust a stated view as new information arrives mid interview.

SIG's interviews are known for repeated probability puzzles and card based games that test whether a candidate updates a stated probability correctly as new information is revealed, mirroring the firm's own decision theory driven approach across products from index options to event markets. A candidate who freezes when asked to defend a probability estimate out loud, rather than simply arriving at the right number silently, tends to struggle in SIG's process even with strong raw math.

Jane Street's interviews layer mental math drills with trading games where the interviewer plays a counterparty and a candidate must make a market, then defend or adjust their price as the interviewer trades against them. The test is less about a single correct probability and more about whether a candidate manages a position and updates it sensibly once shown to be wrong, closer to what a first-year does on a live desk.

Both firms also use the interview to see how a candidate handles being wrong in front of an audience, since a trader who cannot recover from a mistake mid session is unlikely to recover from a mistake mid trading day. The difference is in the trigger: SIG surfaces the mistake through a probability that does not add up under questioning, while Jane Street surfaces it through a price that the interviewer trades against immediately.

SIG built its trading business on applying the same decision theory framework across different markets, including sports and event outcomes alongside financial options, so the firm's interviews are built to find candidates who reason well about probability in the abstract, independent of the specific asset.