This page covers the superday for the Citadel Securities Quantitative Trader internship (US), summer 2028. Here is how the superday works, the market-making and probability questions it leans on, and when you hear back.
Key facts
- Before it: Usually a timed online math test, then one or two phone or video interviews of about 45 minutes with traders.3,4,6,9
- Format: In person for a New York quant trader intern in Oct 2025 (summer 2026); some processes run it as a virtual onsite.6,9
- Content: Weighted toward market making, on a solid base of math and statistics, with brainteasers along the way.6,9
- Interviews: A Chicago trading intern superday in Mar 2021 had three traders, and a New York quantitative trader's virtual onsite in late 2025 had several 30- to 45-minute rounds. The firm's quant research onsite is usually three to five 60-minute interviews.2,8,9
- Hearing back: A decision came about a week after a New York quantitative trader's virtual onsite in late 2025; the firm's quant research guide promises next steps within two weeks of the onsite.9,2
The internship itself trains you on mock trading and game theory, so the superday tests the same instincts: quoting a price, sizing a bet and updating when new information arrives.1,6,7
What the Citadel Securities superday looks like
Before the superday
You apply on the shared trading form, usually take a timed math, probability and statistics test about a week later, then have one or two phone or video interviews of about 45 minutes with traders. The Oct 2025 New York process had two such rounds before the superday.1,3,4,6,9
The day
For a New York quant trader intern in Oct 2025 the superday was in person and more about market making than the earlier rounds, though it still needed a solid base in math and statistics. Some processes run the final round as a virtual onsite.6,9
How many interviews
The firm's quant research onsite is usually three to five 60-minute interviews mixing technical and behavioral questions. A Chicago trading intern superday in Mar 2021 was three traders.2,8
The market-making rounds
Expect to quote prices on something uncertain and have the interviewer trade against you. In Aug 2026 a New York trading process set a market on a Fermi estimate, then a game theory question on how to set your spread and size.7,9
After the superday
For a New York quantitative trader in late 2025, a decision came about a week after a virtual onsite. On the quant research side, next steps come within two weeks, then hiring managers across teams decide fit, and if more than one team wants you, you choose with your recruiter.9,2
Before your superday
- Practice quoting a two-sided market out loud: a bid, an ask and a size, then a new quote after each trade.
- Drill expected value and conditional probability until the setup takes seconds.
- Practice Fermi estimates with ranges, since a market on an estimate needs a width.
- Revise statistics: means, variances and Bayes, which carry the market-making rounds.
- Have one coding language ready; the form asked for your top two.
- Prepare why Citadel Securities and one internship or project story with a result in numbers.
- Bring questions for each interviewer about their desk.
The questions
Expect three kinds of questions: market making, probability and statistics, and why Citadel Securities. The firm's campus interview guide says its technical interviews are practical and oriented toward problem solving, and that you should take hints and say what you do and do not know.2,6,7
- Market making: Quote a bid and an ask on a game or an estimate, trade, then update on new information.
- Expected value: Dice, cards and coin games, often with a choice to stop or continue.
- Probability and statistics: Bayes, conditional probability and distributions, worked out loud.
- Fermi estimates: A rough number for something you cannot look up, with a range.
- Behavioral: Why Citadel Securities, your internships and projects, and your story.
Which division question you get
- Quantitative Trading, New York
- Market making on a Fermi estimate, then game theory on setting spread and size (Aug 2026). The superday was more market making, on top of hard math (Oct 2025).7,6
- Quantitative Research
- A 45 to 60 minute video first round on programming and problem solving with a CoderPad link, then three to five 60-minute onsite interviews, technical and behavioral.2
- Trading intern, Chicago (Mar 2021)
- Behavioral questions, a brainteaser and investment ideas in the first call; the superday with three traders asked behavioral questions and which businesses or industries were good investments.8
- Credit & Rates Rotational TradingBest guess
- Expect the same market-making and probability core, plus questions on how rates and credit spreads move.
The Credit & Rates line is our best guess from the desk's place on the shared trading form and the pattern in the other trading rounds.
Example questions and how to answer them
Market making"Make me a market on the sum of two dice. I will trade against you, then tell you something new."6,7
- 1Find the fair value first: the expected sum.
- 2Quote a bid and an ask around it, wide enough for your uncertainty.
- 3When the interviewer trades, ask what that tells you before you re-quote.
- 4When new information comes, recompute the fair value and move your quote.
Tip: Say the size you will trade, not only the price. The firm's Aug 2026 trading round asked about spread and size together.
Example answer, written by Intervyo (not a real candidate)
Written by Intervyo as an example. Each die averages 3.5, so the sum averages 7. I will make it 6.5 at 7.5, for one lot. If you buy at 7.5 again and again, I ask whether you know something; I might move to 7 at 8. Now you tell me one die is a 6. The other still averages 3.5, so fair value is 9.5, and I quote 9 at 10. If you say the dice are not fair, I widen the spread until I learn more.
Expected value"You roll a die and may roll once more, keeping the second roll. What is the game worth?"5,4
- 1Value the last decision first: a second roll is worth 3.5.
- 2Keep the first roll only if it beats 3.5, so keep 4, 5 or 6.
- 3Average the two branches by their chances.
- 4State the answer and the rule you would play by.
Example answer, written by Intervyo (not a real candidate)
Written by Intervyo as an example. A reroll is worth 3.5, so I keep a first roll of 4, 5 or 6 and reroll a 1, 2 or 3. Half the time I keep, with an average of 5; half the time I reroll, worth 3.5. So the game is worth 0.5 times 5 plus 0.5 times 3.5, which is 4.25. I would pay up to about 4.25 to play.
Fermi estimate"Make a market on how many gas stations there are in the US."7,9
- 1Break the number into pieces you can guess: people, cars, fill-ups, a station's daily capacity.
- 2Multiply through with round numbers, out loud.
- 3Turn your doubt into a width: the less sure you are, the wider the quote.
- 4Be ready to tighten or move when the interviewer trades.
Tip: In Aug 2026 a New York trading round built its market-making question on a Fermi estimate. The width of your quote matters as much as the middle.
Example answer, written by Intervyo (not a real candidate)
Written by Intervyo as an example. Say 280 million vehicles, each filling up about once a week, so roughly 40 million fill-ups a day. If a station handles about 300 a day, that is around 130,000 stations. I am unsure of the per-station number by a factor of about 1.5 either way, so I will make it 100,000 at 170,000. If you sell to me at 100,000, I will lower my estimate of station traffic and move down.
Probability"A test catches a condition 99% of the time and gives a false positive 5% of the time. 1% of people have it. You test positive. How likely is it you have it?"9,2
- 1Write down the base rate before the test.
- 2Work out true positives and false positives out of a round population.
- 3Divide true positives by all positives.
- 4Say why the answer is lower than most people expect.
Example answer, written by Intervyo (not a real candidate)
Written by Intervyo as an example. Take 10,000 people: 100 have it and 99 test positive. Of the 9,900 who do not, 5%, or 495, also test positive. So 99 of 594 positives are real, about 17%. The base rate is so low that false positives outnumber true ones.
Behavioral"Why Citadel Securities?"2,1
- 1Name what the firm does: market making across many asset classes.
- 2Give one reason tied to the internship, such as two rotations or the mock trading program.
- 3Link it to your own story: a project, a class or a competition.
- 4Close on what you want to learn on the desk.
Tip: The firm asks you to read its mission and core values, reflect on how your internships or research moved a business outcome, and refine your own story before the interviews.
More Citadel Securities superday questions
Market making
Probability and expected value
Behavioral and markets
Coding
“A test mixing coding with probability questions.”6
Online test before the superday, Oct 2025
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How long to hear back after the superday
The superday comes within a few weeks of applying, and the whole process has taken under a month. A decision has come about a week after the final round.6,9
Mar 2021
Trading intern, Chicago
A call with a manager, then a superday with three traders, in under a month.8
Aug 2024 (summer 2025)
Quant trader intern, New York
Math test a week after applying, then a phone interview with a trader, where the process ended.4
Oct 2025 (summer 2026)
Quant trader intern, New York
Test, two 45-minute interviews, then an in-person superday weighted toward market making, all in under a month.6
Late 2025
Quantitative trader, New York
A short recruiter call, then a virtual onsite of several 30- to 45-minute rounds, and a decision about a week later.9
Tell your recruiter about any competing offer or process as soon as you have one; the firm tries to meet your deadline.2
Best guessIf a week passes after your superday with no news, a short note to your recruiter is reasonable, especially if you have a deadline elsewhere.
What happens after the superday
Online application
One shared trading form across Citadel and Citadel Securities, with a resume and short questions.1
Online math test
Usually a timed math, probability and statistics test, about a week after applying.3,4,5
Trader interviews (1 or 2)
Phone or video calls of about 45 minutes with traders: probability, expected value, market making and your resume.3,5,6,7
SuperdayYou are here
This page. In person in Oct 2025, weighted toward market making.6
Offer
A decision about a week after the final round, then an 11-week summer with two rotations.9,1
Quant trading vs quant research final rounds
One posting covers trading and quantitative research, but the rounds lean differently: trading on market making and probability, research on coding and research skills.
2028 summer analyst status
For summer 2027 the US posting was online by Jul 6, 2026, with first rounds from mid-July to the end of September, so summer 2028 superdays should follow from late summer 2027.9
FAQ
What is the Citadel Securities quant trader superday like?
For a New York quant trader intern in Oct 2025 it was in person and weighted toward market making, after a math test and two 45-minute rounds, and it still needed a solid base in math and statistics. Some processes run it as a virtual onsite.6,9
How many interviews are in the superday?
Expect three or more. A Chicago trading intern superday in Mar 2021 had three traders, and a New York quantitative trader's virtual onsite in late 2025 had several 30- to 45-minute rounds. The firm's quant research onsite is usually three to five 60-minute interviews.2,8,9
What market-making questions come up?
Quoting a bid and an ask on something uncertain, then trading and updating. In Aug 2026 a New York round built a market on a Fermi estimate and then asked how to set spread and size.7
Is there coding in the superday?
Prepare one language well. The Oct 2025 online test before the superday mixed coding and probability, and the quant research route uses CoderPad. The form asks for your top two interview languages.6,2,1
When do you hear back after the superday?
About a week, for a New York quantitative trader's virtual onsite in late 2025. On the quant research side, next steps come within two weeks, followed by a review in which hiring managers decide team fit.9,2
What if you have a competing offer?
Tell your recruiter as soon as you receive another offer or move forward elsewhere. Citadel Securities asks for that and tries to accommodate your deadlines.2
Superday at other firms
Sources
Firm pages first, then dated candidate reports. Last checked Nov 4, 2026.
- 1Citadel Securities: Quantitative Trader - Intern (US) (Trading and Research), posting and application form
- 2Citadel Securities: Our Campus Quantitative Research Interview Process (Nov 2024)
- 3Candidate report on a public forum: Quant Trader Internship interview, New York (Aug 2022)
- 4Candidate report on a public forum: Quant Trader Intern interview, New York (Aug 2024)
- 5Candidate report on a public forum: Quant Trading Intern interview, New York (Aug 2024)
- 6Candidate report on a public forum: Quant Trader Intern interview, New York (Oct 2025)
- 7Candidate report on a public forum: Trading interview, New York (Aug 2026)
- 8Candidate report on a public forum: Trading Intern interview, Chicago (Mar 2021)
- 9Trading Interview: Citadel Securities Internship 2027: Pay, Roles And Interview Process · prep site
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