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SIG (Susquehanna) interview notes, page 6 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·Recruiter / HR Screen

Jun 2026
Early stages of the SIG trading system engineering internship process. The recruiter call was low-key, just motivation and a light probability question, with a C++ live coding round coming up next.
  • Why are you interested in this role and company?
  • A basic probability question (specific details not shared).

“Pretty standard stuff, recruiter was chill about it.”

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SIG (Susquehanna)·Data Scientist·Technical Phone Screen

Jun 2026
A brain teaser style math problem from a SIG Data Scientist interview. Short and self-contained but the kind of thing that trips you up if you rush the setup.
  • A barn contains spiders, chickens, and cows. Spiders have 8 legs, chickens have 2, and cows have 4. The total leg count is 520. The number of chickens is twice the number of cows, and the number of spiders is twice the number of chickens. How many chickens are there?

“I set up the variable for cows as x, then chickens = 2x, spiders = 4x.”

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SIG (Susquehanna)·Data Scientist·Technical Phone Screen

Jun 2026
SIG logic puzzle interview for a Data Scientist role. One question, four variants, and the kind of problem that sounds like a riddle from a philosophy class. Pretty classic for a quant-adjacent shop.
  • On an island of knights (always truthful) and knaves (always lying), person B says to A: 'You always lie,' and then makes a second claim. There are four possible second claims: (1) A is a knave and B is a knight, (2) A is a knight and B is a knave, (3) A is a knave and B is a knave, (4) A is a knight and B is a knight. For each variant, determine the consistent identities of A and B, or state that no consistent solution exists.

“This wrecked me a little.”

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SIG (Susquehanna)·Software Engineer·Technical Phone Screen

Jun 2026
SIG quant researcher interview with a combinatorics path-counting problem that looks straightforward until you actually try to count it. The constraint makes it way harder than a standard grid walk.
  • A frog moves from (0,0) to (4,6) on a grid, taking steps either right or up one unit at a time. It cannot take three consecutive steps in the same direction. How many valid paths exist?

“My first instinct was to just write out the recursion and I kept second-guessing my base cases.”

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SIG (Susquehanna)·Software Engineer·Technical Phone Screen

Jun 2026
Sig SWE interview centered on implementing a custom vector from scratch, which sounds manageable until you realize they care deeply about every layer of memory management. Three distinct parts, each peeling back another level of C++ internals.
  • Implement the core memory model for a custom vector: define the data members, write raw allocation using operator new, implement reserve, and add push_back with geometric capacity growth. Allocation and construction must be kept separate.
  • Implement the Rule of Five for your custom vector: destructor, copy constructor, copy assignment, move constructor, and move assignment, ensuring deep copy semantics and O(1) moves.
  • How do you make the destructor and reallocation logic correct when T's constructors or move constructors can throw? Specifically, how do you avoid leaking or corrupting the container mid-reallocation?
  • Why might a 1.5x growth factor be preferable to 2x for a general-purpose allocator?
  • How would you add emplace_back with perfect forwarding, and what does it gain over push_back?
  • What are the iterator and reference invalidation rules on reallocation, and how would that affect the API contract for your vector?
  • How would adding an Allocator template parameter change where construction and destruction happen in your vector implementation?

“The separation of allocation from construction is where I expected to trip up and I kind of did.”

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SIG (Susquehanna)·Software Engineer·Technical Phone Screen

Jun 2026
SIG coding round, one algorithmic problem focused on subarray counting with a zero-parity twist. Pretty clean problem once you see the pattern, but getting there under pressure is a different story.
  • Given an integer array, how many contiguous subarrays contain an odd number of zeros? Solve it in O(n) time and explain your approach and complexity.

“I stared at the example for longer than I should have.”

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SIG (Susquehanna)·Software Engineer·Technical Phone Screen

Jun 2026
Posted this looking for intel on SIG's trading system engineering internship pipeline. Recruiter call was relaxed, just some light motivation questions and a basic probability problem. Now prepping for a live C++ coding round and not totally sure what to expect.
  • Why are you interested in this role and company?
  • A basic probability question during the recruiter screen.

“Pretty standard opener, recruiter was casual about it.”

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SIG (Susquehanna)·Software Engineer·Technical Phone Screen

Jun 2026
SIG quant engineer interview with a probability and statistics question pulled straight from a contingency table setup. Pretty focused, no fluff.
  • You're given a two-way contingency table from a survey of 1000 people, with exercise preference on one axis and age group on the other. How do you compute the conditional probability that a respondent is in the 33-37 age group, given that their preferred exercise is swimming?

“Pretty mechanical once you see it.”

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SIG (Susquehanna)·Software Engineer·Technical Phone Screen

Jul 2026
SIG quant engineer interview with a classic knights and knaves logic puzzle. Short and sharp, felt more like a screening than a deep technical round.
  • On an island where knights always tell the truth and knaves always lie, person B makes two statements: 'A and I are the same type' and 'A always lies.' What type is each person?

“I stared at this for a second because both statements together create a contradiction if you assume B is a knight.”

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SIG (Susquehanna)·Software Engineer·Technical Phone Screen

Jul 2026
Quant researcher screen at Sig with a river/canoe word problem that looks like a simple distance-rate question until you realize you have to figure out the departure time working backwards from an arrival constraint. Pretty classic SIG-style brainteaser energy.
  • Two friends paddle upstream for 4 hours, then turn around and go downstream for 5 hours to reach their campsite. The next day they paddle back to the original starting point, which is 23 miles upstream, arriving at 6pm. The river current is always 2 mph and they paddle at a constant speed in still water. What time did they leave that morning?

“I set up the algebra fine but kept second-guessing whether the 23 miles was net displacement or total distance traveled.”

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