From Top University to Top Quant Firm: A Firsthand Look at Jane Street Interns

This article takes you inside the technical internship program at Jane Street through the firsthand experiences of three interns who successfully converted to full-time employees.

Jane Street is a globally renowned quantitative trading firm and liquidity provider, founded in 2000 and headquartered in New York City. The firm has over 2,600 employees worldwide, with operations spanning New York, London, Hong Kong, Amsterdam, Chicago, and Singapore.

As a major market maker, Jane Street trades across more than 200 venues globally, covering equities, bonds, options, futures, commodities, digital assets, and currencies. In 2020, the total value of securities traded by the firm exceeded $17 trillion.

Jane Street is known for its technology-driven trading strategies, extensively using the OCaml programming language to develop trading systems and tools. The firm emphasizes collaboration and problem-solving, committed to innovation in both technology and trading.

The Functional Programming Path: From Campus to Internship

Intern A's Story

Background: Intern A attended Carnegie Mellon University (CMU), known for its strong programming language research group and extensive functional programming curriculum. At school, Intern A developed a strong interest in functional programming, actively learning and even teaching a course called "Hype for Types" aimed at promoting functional programming concepts.

How She Learned About the Firm: In class, students often asked: "When will functional programming ever be useful in practice?" People frequently mentioned this firm, but joked "don't mention that firm, because they're the only company that uses functional programming at scale." This piqued Intern A's interest.

Motivation for Applying: Driven by her passion for functional programming, Intern A felt that applying for an internship at this firm was a natural choice. She hoped to apply her knowledge in real projects and work with like-minded people.

Intern B's Story

Background: Intern B attended Harvard University, majoring in Computer Science and Statistics. During her studies, she took a functional programming course and developed an interest in OCaml. Ron Minsky (a well-known technology expert) gave a guest lecture discussing practical applications of OCaml, which further sparked her interest.

How She Learned About the Firm: Intern B participated in the firm's INSIGHT program, a week-long boot camp for women in STEM. Held at the firm's New York office, participants engaged in a series of OCaml exercises and projects, gaining insight into the firm's technical culture and work environment.

Motivation for Applying: During the INSIGHT program, Intern B experienced the firm's open culture and technical strength. Her interactions with employees convinced her to apply for an internship, hoping to dive deeper into real projects.

Intern C's Story

Background: Intern C attended Cambridge University, where he encountered functional programming during his studies. Although OCaml was not as widely used at his school as elsewhere, this did not hinder his interest.

How He Learned About the Firm: A friend of Intern C's had previously interned at this firm and shared interesting experiences and takeaways. This sparked Intern C's strong interest in the firm.

Motivation for Applying: Encouraged by his friend's recommendation and his passion for functional programming, Intern C decided to apply for an internship, hoping to apply his knowledge in a real-world setting and take on new challenges.

The Internship Journey: Diving into Core Projects

Intern A's Experience

Project Overview: Intern A worked on improving the firm's manual order entry system, which allows traders to manually place orders with multiple risk controls.

Challenges & Solutions:

• Problem: Traders could not quickly adjust system-level risk limits during a trading day, which affected trading efficiency during market volatility. The previous process required modifying configuration files, going through code review and release a slow process.
• Intern A's Task: Optimize the system so traders could rapidly adjust system-level risk limits during a trading day while ensuring compliance and security.
• Implementation: She deeply studied existing risk control mechanisms, worked closely with the team, and designed and implemented a module allowing quick risk limit adjustments. She also ensured compatibility with existing systems.
• : Intern A successfully implemented this feature, improving system flexibility. Her work was widely adopted after she joined full-time, with traders praising the new functionality.

Intern B's Experience

Project Overview: Intern B worked on developing Incr_dom, an OCaml library used by the firm for building dynamic web applications.

Challenges & Solutions:

• Problem: The existing Incr_dom library had two interfaces one simple but with limited functionality, the other powerful but complex. Users had to choose between ease of use and performance.
• Intern B's Task: Design and implement a new interface combining the advantages of both maintaining ease of use without sacrificing functionality.
• Implementation: She deeply studied the library's architecture and considered API design principles. She also wrote a PPX (preprocessing extension) to simplify developer usage. She iterated on the design with her mentor throughout the process.
• Outcome: Intern B successfully designed the new interface and improved the library's performance. Her work increased development efficiency and was recognized by the team.

Intern C's Experience

Project Overview: Intern C worked on developing the Request for Quote (RFQ) system. The RFQ system allows clients to request quotes from multiple market makers and select the best price for execution.

Challenges & Solutions:

• Problem: The risk check process for manual requests was not sufficiently automated, presenting efficiency and security risks. Manual requests did not apply the same risk control mechanisms as automated requests.
• Intern C's Task: Integrate manual requests with the automated system so they could use unified risk check mechanisms, ensuring trading security.
• Implementation: He needed to deeply understand the RFQ system architecture and trading flow, and communicate requirements with the team and traders. He redesigned the manual request processing flow so it could be recognized by the system and undergo risk checks.
• Outcome: Intern C successfully automated the risk check process for manual requests, improving system security and efficiency while reducing the possibility of human error.

From Internship to Full-Time: New Challenges and Growth

Intern A's Conversion Path

• Returning to the Team: Intern A chose to return to the team she interned with, continuing to deepen her project.
• New Responsibilities: As a full-time employee, she participated in more long-term and open-ended projects, such as developing an options pricing application. She needed to consider broader system design and performance optimization.
• Collaboration & Innovation: She actively collaborated with different teams and introduced new technical solutions. For example, she adopted Redis for caching in a project, improving system performance and response speed.

Intern B's Conversion Path

• Team Selection: Intern B joined the team where Intern C had interned, taking on the task of advancing the RFQ system project.
• Deep Collaboration: She needed to work closely with more traders and teams, understanding the issues they encountered in the trading process and gathering improvement requirements.
• Technical Growth: In her new team, Intern B continuously improved her technical skills, participating in complex system design, risk control, and user interface optimization.

Intern C's Conversion Path

• New Project Challenge: Intern C joined a new team to start developing the Zeroprot project. Zeroprot is a protocol for efficient communication between different applications, designed to address version compatibility and high-performance communication issues.
• Key Role: Intern C was responsible for developing new features, designing the protocol, and integrating with other systems. He also needed to write tools and libraries to facilitate other developers' use of the protocol.
• Technical Breakthroughs: He solved numerous technical challenges in the project, such as data serialization, version compatibility checking, and efficient network communication, making significant contributions to optimizing the firm's communication protocols.

Cross-Team Collaboration: Communication and Mutual Benefit

• Intern A's Experience: She emphasized the firm's open communication culture. During her project, she collaborated closely with the infrastructure team and risk control team to achieve system performance improvements. She also learned new technologies and best practices through interactions with other teams.
• Intern B's Experience: Daily communication with traders gave her a deep appreciation for the importance of understanding user needs. Through direct interaction, she could quickly respond to business needs and provide efficient technical support. She also participated in user interface improvements to make the system more user-friendly.
• Intern C's Experience: On large projects, Intern C collaborated with multiple teams, coordinating different technical solutions and requirements. He believes that successful projects depend on good teamwork and communication. He also actively participated in internal tech talks, sharing his experiences and insights.

Facing Challenges: Growing Through Practice

• Technical Challenges: Adapting to new tools and technologies, such as OCaml, internal development tools, and complex system architectures, was a common challenge. They gradually mastered necessary skills through learning and practice.

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