C

Citadel Securities

Global market maker delivering liquidity

Quantitative Researcher – PhD Intern - Europe

Full-TimeUpdated on 10/22/2026
No salary listed
Internship
PhD
London, UK
In PersonOn-site internships in Europe; no remote work.
Quantitative FinanceQuantitative Research

About the job

Requirements
  • PhD degree in mathematics, statistics, physics, computer science, or another highly quantitative field
  • Strong knowledge of probability and statistics (e.g., machine learning, time-series analysis, pattern recognition, NLP)
  • Prior experience working in a data driven research environment
  • Experience with translating mathematical models and algorithms into code (Python, R or C++)
  • Independent research experience
  • Ability to manage multiple tasks and thrive in a fast-paced team environment
  • Excellent analytical skills, with strong attention to detail
  • Strong written and verbal communication skills
Responsibilities
  • Conceptualize valuation strategies, develop and continuously improve upon mathematical models, and help translate algorithms into code
  • Back test and implement trading models and signals in a live trading environment
  • Use unconventional data sources to drive innovation
  • Conduct research and statistical analysis to build and refine monetization systems for trading signals

About the company

C

Citadel Securities

View
Website

Citadel Securities is a global market maker that provides liquidity and trading services to institutional clients in equities, options, and FICC markets. It uses advanced technology and data analytics to place and manage bid-ask quotes, execute trades, and optimize order routing, earning a small margin on each trade and charging fees for services. Its products and services help clients meet liquidity needs with low-cost, efficient execution. The company distinguishes itself by aiming for the fairest, most transparent, and open markets, continually reinvesting in technology and expertise to improve market efficiency and transparency. The goal is to bridge the financial markets with the real economy by creating reliable liquidity and transparent trading environments.

Company Size

1,001-5,000

Company Stage

Growth Equity (Venture Capital)

Total Funding

$1.2B

Headquarters

Miami, Florida

Founded

2002

Get referred to Citadel Securities

See people who can refer or advise you

Simplify Jobs

Simplify's Take

What believers are saying

  • Second-quarter 2026 trading revenue hit $7.3 billion, with net income at $3.3 billion.
  • October 2, 2026 Wolfe partnership expands institutional flow and adds research capabilities.
  • DTCC tokenization production and Fireblocks support open new collateral and digital-asset revenue streams.

What critics are saying

  • June 29, 2026 spoofing suit against Citadel Securities and Virtu threatens costly discovery.
  • SEC scrutiny over CAT funding and order-mismarking history keeps compliance pressure persistent.
  • If retail flow and block-trading growth fade, 2026 revenue momentum collapses fast.

What makes Citadel Securities unique

  • Citadel Securities pairs market making with Wolfe Research distribution after October 2, 2026.
  • It spans equities, options, FICC, and tokenization workflows through DTCC and Fireblocks.
  • Its scale handles over one-third of U.S. retail stock trades, strengthening liquidity network effects.

Help us improve and share your feedback! Did you find this helpful?

Benefits

  • Health Insurance
  • Life Insurance
  • 401(k) Retirement Plan
  • Performance Bonus

Growth & Insights and Company News

6 month growth

1%

1 year growth

1%

2 year growth

0%
eFinancialCareers
Oct 22nd, 2026
The ex-Citadel Securities and Tower Research traders that left for fintech don't want to stop trading.

The ex-Citadel Securities and Tower Research traders that left for fintech don't want to stop trading. 22 October 2026 Having your quantitative cake and eating it too. You can take a quant out of trading but you can't take trading away from the quant. The electronic trading industry is a rich source of talent for startups, and some of the traders currently working in fintech startups have been building out quant trading functions within their companies. Take Mark Wilkinson, Citadel Securities' former head of FICC systematic trading, who left for investment platform WealthSimple. He announced via LinkedIn yesterday that he's "building out a quantitative trading function" at the fintech; job listings state that the quant traders hired will conduct research and build algorithms "to produce an edge for our clients and the company." Wilkinson is looking for people with at least three years in quant trading for the buildout. He's not alone. Annanay Kapila, an ex-Tower Research trader and founder of perpetuals exchange QFEX, told us that his firm has begun "open-sourcing some mid-frequency trading strategies to some of our clients." He announced last week on LinkedIn that, in the first 12 days of October, QFEX made more money than it did for the 12 months ending August 2026. He said the firm's trading strategies benefitted greatly from the release of OpenAI's Astra model in early September: "I've never seen any model be able to do quant research as well as Astra." More QaaS (Quant as a Service) startups may be birthed if more ex-traders get backed. Alexandr Wang, chief AI officer of Meta, was famously part of Hudson River Trading's first intern class; he said on a recent podcast that he spoke to HRT's founder (presumably Jason Carroll) and advised him to "just invest in all the interns... give all the interns seed checks." Have a confidential story, tip, or comment you'd like to share? Contact: WhatsApp: http://wa.me/442079977910 (+44 20 7997 7910), Telegram: @AlexMcMurray, Signal: @AlexMcMurrayEFC.88 Click here to fill in our anonymous form, or email [email protected]. Bear with us if you leave a comment at the bottom of this article: comments are moderated intermittently by human beings. Sometimes these humans might be asleep, or away from their desks, so it may take a while for your comment to appear. You must take sole responsibility for comments you post on this site. We will take reasonable steps to weed out anything that we consider to be offensive or inappropriate. The essential daily roundup of news and analysis read by everyone from senior bankers and traders to new recruits. Boost your career. Find thousands of job opportunities by signing up to eFinancialCareers today.

Bloomberg Law
Oct 20th, 2026
ASI raises $325M at $3B valuation in Spark-led round for AI that manages military and airline assets

ASI, a Boston-based startup previously known as Air Space Intelligence Inc., raised $325 million in a series C round that values it at $3 billion. Spark Capital led the round. Craft Ventures, Andreessen Horowitz, and affiliates of Citadel Securities, among others, also took part. The company is due to announce the deal Tuesday. ASI will use the money to expand its artificial intelligence system, which helps the military, airlines, and air-traffic controllers manage assets. The company is part of a resurgence in US defence and aerospace technology startups, which have drawn growing interest from investors and government agencies.

Bloomberg
Oct 20th, 2026
What to expect from spacex earnings.

What to expect from spacex earnings. Oct 20th, 2026 Citadel Looking to Grow in Fixed Income, Esposito Says "We're only really getting started in fixed income," Citadel Securities President Jim Esposito says during an interview with Bloomberg's Dani Burger on the sidelines of Citadel's annual Future of Global Markets Conference in New York. Esposito also says the firm is "maniacally" focused on market making. Top video. Available on:

eFinancialCareers
Oct 16th, 2026
Citadel Securities hired Aditya Singh from Balyasny.

Citadel Securities hired Aditya Singh from Balyasny. 39 minutes ago Last week reported that ex-Goldman Sachs rates trader Aditya Singh had left Balyasny Asset Management. Today, we can report that Singh is joining Citadel Securities. Citadel Securities didn't respond to a request to comment on Singh's arrival when asked multiple times last week. We understand that he will be supporting the rates team. Singh is understood be joining the team run by Nikhil Choraria, another Citadel Securities hire from Goldman Sachs. Initially we were given to understand that Citadel Securities had not hired Choraria, but Choraria arrived there in September and is running the fixed income business. It's thought that Singh resigned from Balyasny before the recent spate of exits at the fund, possibly departing in May. Balyasny declined to comment previously on his departure. Citadel Securities employs a cluster of Goldman's ex-macro people in London. As well as Choraria and Singh, it employs Nohshad Shah, Frank Flight and Ishaan Sethi. Citadel Securities declined to comment. Follow me on X. Follow me on LinkedIn. Have a confidential story, tip, or comment you'd like to share? Contact: +44 7537 182250 (SMS, Whatsapp or voicemail). Telegram: @SarahButcher. Signal: sarahbutcher.22 Click here to fill in our anonymous form, or email [email protected]. Bear with us if you leave a comment at the bottom of this article: comments are moderated intermittently by human beings. Sometimes these humans might be asleep, or away from their desks, so it may take a while for your comment to appear. You must take sole responsibility for comments you post on this site. We will take reasonable steps to weed out anything that we consider to be offensive or inappropriate. The essential daily roundup of news and analysis read by everyone from senior bankers and traders to new recruits. Boost your career. Find thousands of job opportunities by signing up to eFinancialCareers today. Top Articles

The Digital Track
Oct 13th, 2026
BNY, Citadel Securities test tokenized U.S. Treasuries to speed up Wall Street financing.

BNY, Citadel Securities test tokenized U.S. Treasuries to speed up Wall Street financing. October 13, 2026 Coindesk general Positive BNY and Citadel Securities have successfully tested tokenized U.S. Treasuries on blockchain infrastructure, marking a significant milestone in Wall Street's push to modernize collateral management and financing operations. The pilot transaction demonstrates how blockchain-based government bonds can dramatically accelerate the movement of collateral between settlement and financing workflows - a process that currently costs trading firms billions in tied-up capital annually. By tokenizing U.S. Treasuries, both institutions are exploring how distributed ledger technology can compress settlement times, reduce counterparty risk, and unlock intraday liquidity for major financial players. This development arrives as institutional blockchain adoption accelerates in 2026, with tokenized real-world assets emerging as one of the fastest-growing sectors in digital finance. The collaboration between a top-tier custodian like BNY and a market-making powerhouse like Citadel Securities signals that tokenized Treasury bonds are moving beyond proof-of-concept into practical, high-stakes financial infrastructure. Investors and market participants tracking the tokenized RWA space, DeFi collateral solutions, and blockchain-based securities settlement should treat this as a bellwether moment for institutional crypto integration. Watch for additional Wall Street firms to announce similar tokenization pilots as regulatory clarity around digital securities continues to evolve heading into 2027. The transaction shows how blockchain-based government bonds could help trading firms move collateral faster between settlement and financing.