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SIG (Susquehanna) interview notes, page 1 of 7

Large Enterprises

Most of these SIG (Susquehanna) write-ups come from Software Engineers (51), then Data Scientists (12). The most reported rounds are the technical phone screen (56), the system design round (3), the online assessment (1) and the onsite coding round (1).

63 interview notes · updated Sep 2026

SIG (Susquehanna)·Software Engineer·Onsite - System Design / Architecture

May 2025
Virtual onsite at Sig for a software engineering role. Got an object-oriented design question about a grocery system, and the interviewer was pretty hard to read the whole time so I had no idea how I was doing.
  • Design an object-oriented system for a grocery store.

“Talked through it step by step and kept pausing to ask if my reasoning tracked.”

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SIG (Susquehanna)·Software Engineer·Technical Phone Screen

Apr 2026
SIG quant researcher interview, technical screen focused on CS fundamentals with a heavy emphasis on sorting algorithms and how they behave under different data conditions. Not what I expected going in, felt more like a systems-thinking exercise than a pure math grind.
  • Walk through how you would sort an array of integers. Pick a sorting algorithm, explain how it works at a high level without writing code, and cover its average, worst, and best case time complexity along with space complexity and whether it's stable. Then discuss how your choice would change if the data is nearly sorted, has lots of duplicates, or is too big to fit in memory.

“This looks like a textbook question until they ask the follow-up about nearly sorted data and you realize you picked quicksort as your lead example.”

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SIG (Susquehanna)·Software Engineer·Technical Phone Screen

Apr 2026
SIG quant researcher interview with a probability question that looks straightforward but trips you up if you're sloppy with the setup.
  • On a platform where 70% of stories are real and 30% are fake, a fake story has an 80% chance of getting 100+ likes while a real story only has an 8% chance. Given that a randomly selected story has 100+ likes, what's the probability it's real news?

“Classic Bayes setup.”

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SIG (Susquehanna)·Software Engineer·Technical Phone Screen

Apr 2026
SIG quant engineer interview, probability-heavy round that felt like they pulled questions straight from the Green Book. Two dice problems back to back, both requiring clean combinatorial arguments.
  • Using a fair 9-sided die rolled a fixed number of times, what is the probability of rolling a 'straight', meaning a run of consecutive distinct values across all rolls? Walk through your assumptions and counting argument.
  • Using the same 9-sided die rolled 5 times, compute the probability of a 'full house', meaning exactly three of one face value and two of another. State your assumptions and show the counting.

“The setup sounds clean but I fumbled the assumptions part at first.”

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SIG (Susquehanna)·Software Engineer·Technical Phone Screen

Apr 2026
SIG quant engineer interview with a logic puzzle that sounds deceptively clean but turns out to need a full case analysis to crack. One question, no fluff.
  • A, B, and C each own some number of cats. The rule is: a person lies when speaking to someone with fewer cats than themselves, and tells the truth otherwise. Given four statements of the form 'X says to Y: [claim]', figure out exactly how many cats A owns by working through every possible ordering of cat counts and finding the one that's consistent.

“This wrecked me a little.”

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SIG (Susquehanna)·Software Engineer·Technical Phone Screen

Apr 2026
SIG quant researcher interview, technical phone screen that went pretty deep into econometrics fundamentals. One question but it had a lot of moving parts and I definitely underestimated how much they'd push on the theory side.
  • Derive the OLS estimator from scratch by minimizing sum of squared residuals, then explain the conditions under which it's BLUE and what efficiency actually means in that context.

“I got through the derivation okay, took the gradient, set it to zero, got to (X'X)^{-1} X'y without too much fumbling.”

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SIG (Susquehanna)·Software Engineer·Technical Phone Screen

Apr 2026
SIG quant researcher interview with a probability puzzle that looks clean on the surface but has enough moving parts to slow you down if you're not careful with the state space.
  • You start with 3 tokens and want to reach 5 before going broke. Each turn you bet the maximum amount that won't overshoot your target (so you bet aggressively but never past 5). Each bet doubles with probability 1/4 or is lost with probability 3/4. What's the probability you hit 5 tokens before 0?

“The bold strategy part is what makes this annoying.”

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SIG (Susquehanna)·Software Engineer·Technical Phone Screen

Apr 2026
SIG quant engineer interview threw a classic brain teaser at me, the kind where you set up a system of equations and just grind through it. Pretty standard for a quant screen.
  • Chickens, cows, and spiders share a cage with a total of 560 legs. The number of chickens is twice the number of cows, and the number of spiders is twice the number of chickens. How many spiders are there?

“Set up three variables and the leg count equation.”

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SIG (Susquehanna)·Software Engineer·Technical Phone Screen

Apr 2026
SIG quant researcher screen, basically just a math puzzle about counting legs in a barn. Short and painless but I second-guessed my algebra the whole time.
  • A barn has spiders (8 legs), chickens (2 legs), and cows (4 legs). Total legs add up to 520. Chickens are twice the number of cows, and spiders are twice the number of chickens. How many spiders are there?

“Set up the variables fine, cows = x, chickens = 2x, spiders = 4x.”

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SIG (Susquehanna)·Software Engineer·Technical Phone Screen

Apr 2026
SIG had me do a technical phone screen with a pretty focused coding problem. Nothing crazy, but it tests whether you actually know how to work with strings and time arithmetic without reaching for a library.
  • Given two time strings in 24-hour 'HH:MM' format where the second time is always later than the first, compute the difference between them in minutes.

“Straightforward on the surface but they wanted you to walk through every step out loud.”

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