One-line summary: Susquehanna (SIG) OA splits into three tracks — Trader emphasizes probability + mental math, QR emphasizes math + statistics, SDE emphasizes Codility coding. The three tracks are completely different — don't mix prep directions.
Susquehanna International Group (SIG, also "SQA") is a Philadelphia-based market maker / quant firm famous for its tough probability questions, heavy mental-math testing, and unique poker assessment. This article breaks down the 2026 OA across all three tracks.
1. SIG OA Three Tracks
| Role | OA Modules | Time | Core focus |
|---|---|---|---|
| Quantitative Trader Assistant (QTA) | PSA + Mental Math + Poker | 90+30+15 min | Probability, expectation, mental math |
| Quant Research / Strategist | PSA + advanced math | 120 min | Statistics, stochastic processes |
| SDE / Quant Dev | Codility 2-3 questions | 70-90 min | Algorithms, data structures |
| Other | Behavioral + simple logic | 30 min | LP-style |
Critical: Read the JD carefully — Trader and QR OAs are different and should not be cross-prepared.
2. PSA (Problem Solving Assessment) Topic Breakdown
PSA is SIG's signature test — about 9 questions covering:
| Topic | Share | Difficulty |
|---|---|---|
| Geometric probability (interval meeting) | 15% | ⭐⭐⭐ |
| Expected value (recursion / Markov) | 20% | ⭐⭐⭐⭐ |
| Bayesian conditional probability | 15% | ⭐⭐⭐ |
| Combinatorics | 15% | ⭐⭐⭐ |
| Logic puzzles (ages, truth/lies) | 10% | ⭐⭐ |
| Geometry / shortest path / refraction | 10% | ⭐⭐⭐⭐ |
| Path counting / discrete DP | 15% | ⭐⭐⭐ |
Sample Q1: Theater Meeting (geometric probability)
Statement: A and B each arrive uniformly between 18:00-19:00. A waits up to 12 min, B waits up to 36 min. What is the meeting probability?
Solution: In the [0,60]² plane, meeting region is -36 ≤ B - A ≤ 12.
- Non-meeting area = two triangles = 48²/2 + 24²/2 = 1440
- Total = 3600
- P(meet) = 1 - 1440/3600 = 3/5
Sample Q2: Two Black Tiles in a Row (expected value)
Statement: Each draw is black with probability p = 1/3. Expected draws until two consecutive blacks?
Let E = initial expectation, A = expectation after a black:
- A = 1·p + (1-p)(1+E)
- E = (1-p)(1+E) + p(1+A)
Solving: E = (1+p)/p² = (4/3)/(1/9) = 12.
Sample Q3: Bayesian (most-biased coin)
Statement: Three coins with heads probabilities 9/10, 4/5, 11/20. Pick one uniformly, flip → tails. P(picked the 9/10 coin)?
- P(T|9/10) = 1/10
- P(T) = (1/10 + 1/5 + 9/20)/3 = 1/4
- P(9/10|T) = (1/3 × 1/10) / (1/4) = 2/15
For all 9 sample questions, see our SIG PSA full review article.
3. Mental Math Test
Format: Trader-track only — 60 questions in 5 minutes.
Topics:
- Integer +/-/×/÷ (incl. negatives and decimals)
- Percentage conversions (e.g., 37.5% × 64)
- Simple fractions (e.g., 7/12 + 5/8)
Bar: Usually need 40+/60 correct.
Training tools:
- zetamac.com (set 2-digit × 2-digit, 5 min)
- 30 min/day for 2 weeks can take you from 25 to 45+
4. Poker Test
SIG is one of the few firms that uses poker scenarios to assess risk preference and decision consistency.
Topics:
- Given pot odds + opponent range, compute call / raise / fold EV
- Simplified Texas Hold'em probabilities (post-flop equity)
Tip: You don't need to be a poker shark, but understanding "act when EV > 0" is essential.
5. SDE Track: Codility Questions
Format: 2-3 questions, 70-90 minutes, LeetCode Easy-Medium.
Sample: Trading Sequence
Statement: Given a stream of buy/sell (side, price), simulate order-book matching and output final inventory + P&L.
import heapq
def simulate(orders):
bids, asks = [], []
pnl = 0
for side, price in orders:
if side == 'B':
while asks and asks[0] <= price:
pnl += price - heapq.heappop(asks)
heapq.heappush(bids, -price)
else:
while bids and -bids[0] >= price:
pnl += -heapq.heappop(bids) - price
heapq.heappush(asks, price)
return pnl
Other High-Frequency Topics
| Pattern | LeetCode analog |
|---|---|
| Sliding window max | LC 239 |
| Interval merge | LC 56 |
| String pattern matching | LC 28 |
| Binary search on answer | LC 875 |
6. FAQ — SIG OA Common Questions
Q1: What's the bar for SIG PSA?
Usually 6/9 correct is the interview threshold. Trader track requires more (7+/9).
Q2: How important is Mental Math?
Decisive for Trader track. Score < 30 → reject. Score > 50 can offset one PSA miss.
Q3: Open book?
No. PSA is closed-book; the platform locks the screen and timer.
Q4: Does SIG sponsor H1B / GC?
Yes. SIG has a long history of sponsoring international students (OPT/STEM OPT/H1B/GC) and is friendly to Chinese candidates.
Q5: Can I retake?
Usually 6-month cooldown.
Q6: Calculator allowed in PSA?
Trader track: no. QR track allows a basic calculator (no graphing/programming) on some questions.
7. SIG Prep Path (4 Weeks)
| Week | Trader / QR Track | SDE Track |
|---|---|---|
| 1 | Probability fundamentals + zetamac | LeetCode Easy 30 |
| 2 | Expected-value recursion + Bayes | LeetCode Medium 30 + monotonic queue |
| 3 | PSA past papers | Codility mocks 4 sets |
| 4 | Poker decisions + full mock | Real-question review + timing |
8. External Resources
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Contact
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