Prepare for and practice interview questions from Selby Jennings.

Selby Jennings Interview Questions

Selby Jennings Interview Guides

Suppose there exists a new airline named Jetco that flies domestically across North America. Jetco recently had a study commissioned that tested the boarding time of every airline, and it came out that Jetco had the fastest average boarding times of any airline.

What factors could have biased this result, and what would you look into?

What could potentially bias the average boarding time in favor of an airline that only flies domestically?

What could potentially bias the average boarding time in favor of an airline that only flies domestically?

Boarding Times Bias

A new airline came out as the fastest average boarding times compared to other airlines.  What factors could have biased this result and what would you look into?

Statistics

Let’s say you work for a social media company that has just done a launch in a new city. Looking at weekly metrics, you see a slow decrease in the average number of comments per user from January to March in this city.

The company has been consistently growing new users in the city from January to March.

What are some reasons why the average number of comments per user would be decreasing and what metrics would you look into?

What metric could be used to measure if active users are still engaging on the platform despite an overall decrease in the average number of comments per user?

What metric could be used to measure if active users are still engaging on the platform despite an overall decrease in the average number of comments per user?

Decreasing Comments

How would you investigate a decline in the average number of comments per user?

Product Metrics

You are testing hundreds of hypotheses with many t-tests. What considerations should be made?

What is a key disadvantage of the F-test when compared to multiple t-tests?

What is a key disadvantage of the F-test when compared to multiple t-tests?

Hundreds of Hypotheses

You are testing hundreds of hypotheses with many t-tests. What considerations should be made?

Our client is a high-growth technology company building critical infrastructure for decentralised finance (DeFi) and Web3. They work with leading wallets and exchanges and are shaping the future of blockchain technology. This is an opportunity to join a fast-paced environment and make a real impact on cutting-edge systems. About the Role As a Senior Software Engineer, you will:<ul><li>Design and implement backend systems and APIs (Golang preferred, but flexible)</li><li>Build modern web frontends using frameworks like Next.js</li><li>Collaborate with product and engineering teams to deliver new features</li><li>Scale infrastructure to support growing complexity</li><li>Solve challenging technical problems in a dynamic environment</li></ul> About You<ul><li>5+ years of professional software engineering experience</li><li>Strong expertise in Golang or TypeScript/JavaScript</li><li>Comfortable working across the stack</li><li>Experience in crypto/DeFi is highly desirable, but not mandatory</li><li>Open to candidates from outside crypto/DeFi for the right fit</li><li>If you are a knowledgeable DeFi expert, Golang experience is not required</li><li>Excellent communication and collaboration skills</li></ul> Benefits<ul><li>Competitive salary and equity</li><li>Flexible work arrangements and generous holiday allowance</li><li>Opportunity to work on innovative blockchain technology</li></ul> If you're passionate about building scalable systems and want to help shape the future of decentralised finance, we'd love to hear from you.

Senior Software Engineer - Commodities TechnologyAbout the Role A household name in the quantitative trading space is seeking a Senior Software Engineer to join its Commodities Technology team. This group is building cloud-native systems that power risk analytics for commodities trading and is leading a multi-year initiative to develop advanced risk platforms, broaden coverage for new asset classes, and support overall business growth.The Senior Software Engineer will design and implement solutions for risk modeling, P&L calculations, stress testing, market data processing, and large-scale data management. This individual will collaborate with stakeholders to deliver high-performance systems in a fast-paced environment.Key Responsibilities<ul><li>Develop distributed systems for risk analytics and data processing.</li><li>Partner with risk and portfolio teams to deliver scalable solutions.</li><li>Automate reporting and enhance workflows through data-driven insights.</li></ul>Required Qualifications<ul><li>4+ years of software development experience in financial services.</li><li>Some exposure to commodities markets, derivatives, and risk analytics.</li><li>Expertise in Python, distributed architecture, and performance optimization.</li><li>Proficiency in SQL, Pandas, REST APIs, and AWS services.</li><li>Familiarity with Kubernetes, Kafka, Redis, MongoDB, and MS SQL.</li><li>Bachelor's or advanced degree in Computer Science or related field.</li></ul>Preferred Skills<ul><li>Experience with firmwide risk systems and energy markets.</li><li>Knowledge of Beacon Platform and Bloomberg/Morningstar data.</li><li>Familiarity with DevOps tools and Agile practices.</li><li>Additional languages (Rust, Java, Scala, C++ or C#) are a plus.</li></ul>

Role: C++ DeveloperLocation: Amsterdam, The NetherlandsMy client, a leading proprietary trading firm founded by experienced high-frequency traders and with presence in 3 continents, is now looking to expand its development team locally.This role will focus specifically on working closely with our traders in assisting in the design and implementation of Options trading strategies.The Candidate:* A desire to join a leading Proprietary trading company and be part of the trading industry. * Experience with contemporary C++ as well as python in a Linux environment;* Extensive experience implementing any asset class in trading strategies. Benefits:* Excellent variable pay based on performance, with a fair bonus-structure awarding company* A dynamic and vibrant team in an informal setting;* A true sense of responsibility in your work backed by trusting colleagues;* Formal training and continuous feedback;* Public transport & health insurance reimbursement.

A leading Investment Management Firm is looking to bring on a Lead Data Engineer to join its team in Tampa, Denver, Memphis, or Southfield. This is an excellent chance to work alongside industry leaders while getting to be both hands on and helping lead the team. Key Responsibilities<ul><li>Project Oversight: Direct end-to-end software development activities, from initial requirements through deployment, ensuring projects meet deadlines and quality standards.</li><li>Database Engineering: Architect and refine SQL queries, stored procedures, and schema designs to maximize efficiency and scalability within Oracle environments.</li><li>Performance Tuning: Evaluate system performance and apply strategies to enhance data storage and retrieval processes.</li><li>Data Processing: Utilize tools like Pandas and Spark for data wrangling, transformation, and analysis.</li><li>Python Solutions: Develop and maintain Python-based applications and automation workflows.</li><li>Pipeline Automation: Implement and manage continuous integration and delivery pipelines using Jenkins and similar technologies to optimize build, test, and release cycles.</li><li>Team Development: Guide and support junior engineers, promoting collaboration and technical growth.</li><li>Technical Documentation: Create and maintain comprehensive documentation for all development initiatives.</li></ul> Core Skills<ul><li>Experience: Over a decade in software engineering, with deep expertise in Python and Oracle database systems.</li><li>Technical Knowledge: Strong command of SQL, Oracle, Python, Spark, Jenkins, Kubernetes, Pandas, and modern CI/CD practices.</li><li>Optimization Expertise: Skilled in database tuning and applying best practices for performance.</li><li>Leadership Ability: Proven track record in managing teams and delivering complex projects.</li><li>Analytical Strength: Exceptional problem-solving capabilities with a data-centric mindset.</li><li>Communication: Clear and effective written and verbal communication skills.</li><li>Education: Bachelor's degree in Computer Science, Engineering, or equivalent professional experience.</li></ul> Preferred Qualifications<ul><li>Certifications: Professional credentials in Oracle, Python, Kubernetes, or CI/CD technologies.</li><li>Agile Background: Hands-on experience with Agile or Scrum frameworks.</li><li>Cloud Platforms: Familiarity with AWS, Azure, or Google Cloud services.</li></ul>

About the Role We are looking for a Senior Software Engineer to design and implement algorithmic trading solutions in a fast-paced environment. This position involves working closely with stakeholders to translate trading objectives into robust technical systems and strategies. You will help shape execution logic and ensure systems operate reliably under real-world conditions.Key Responsibilities<ul><li>Develop and refine algorithmic trading strategies.</li><li>Collaborate with internal teams to understand requirements and deliver effective solutions.</li><li>Lead technical initiatives and contribute to system architecture decisions.</li><li>Troubleshoot complex issues and ensure operational stability.</li><li>Mentor junior engineers and promote best practices.</li></ul>Qualifications<ul><li>5+ years of software engineering experience, preferably in financial or trading systems.</li><li>Strong programming skills in java and python</li><li>Solid understanding of algorithms, data structures, and system design.</li><li>Experience building distributed or high-throughput applications.</li><li>Ability to work collaboratively and communicate technical concepts clearly.</li><li>Bachelor's or Master's degree in Computer Science or related field.</li></ul>

Our client, a leading hedge fund, is looking for a Senior Applied AI Researcher to join their Applied AI team in London. You will be transforming how professionals interact with artificial intelligence in high-performance environments. This team has developed a suite of AI-powered tools, including custom assistants with deep research capabilities, and is focused on building reasoning models and collaborative AI workspace. We are seeking a Senior Research Scientist to contribute to the development of next-generation AI tools that support decision-making and research workflows. You'll work on impactful projects that bring advanced machine learning research into production, directly influencing how users leverage AI in complex domains. This role offers a unique opportunity to push the boundaries of human + AI collaboration. You'll work within a rich ecosystem of data, models, compute resources, and expert users, enabling rigorous experimentation and innovation. Responsibilities <ul><li>Conduct original research in machine learning, particularly in reinforcement learning, agent architectures, and large language models (LLMs)</li><li>Prototype and develop new ML models and algorithms for real-world deployment</li><li>Collaborate with engineering teams to integrate research into production systems</li><li>Design experiments and analyze results to evaluate model performance</li><li>Engage with end-users to align research with practical applications</li><li>Contribute to the research community through publications, presentations, and open-source projects</li><li>Mentor junior researchers and help shape technical strategy</li><li>Participate in the full research lifecycle from ideation to deployment </li></ul>Requirements: <ul><li>PhD in Computer Science, Machine Learning, Statistics, Applied Mathematics, or a related field</li><li>Strong publication record in top-tier conferences (e.g., NeurIPS, ICML, ICLR, ACL, EMNLP)</li><li>2-5 years of post-PhD experience</li><li>Deep expertise in machine learning, with a focus on NLP and reinforcement learning</li><li>Experience developing ML models in Python (PyTorch)</li><li>Proven ability to translate research into scalable, practical solutions</li><li>Experience deploying ML models in production environments</li><li>Familiarity with financial markets or complex decision-making domains</li><li>Knowledge of vector databases, semantic search, or information retrieval systems</li></ul>

A growing multi-strategy hedge fund is seeking Operations Software Engineers to design, build, and maintain technology that supports its revolutionary operational backbone. If you're looking for a highly collaborative role where you'll work alongside some of the brightest minds in the industry, this is the opportunity for you! This team plays a critical role in ensuring smooth trade lifecycle management, reporting, and reconciliation. What You'll Do <ul><li>Develop and maintain systems for trade capture, reconciliation, settlement, risk, treasury, P&L, and regulatory reporting.</li><li>Collaborate with Operations and Finance to automate workflows and reduce errors.</li><li>Build integrations with external systems such as brokers, fund administrators, custodians, and regulatory platforms.</li><li>Make architectural decisions that enable scalability and long-term reliability.</li></ul> What We're Looking For <ul><li>Bachelor's degree in Computer Science, Engineering, or related field.</li><li>2+ years of professional software engineering experience in financial services.</li><li>Strong programming skills in Python.</li><li>Experience with SQL databases and data modeling.</li><li>Familiarity with the trade lifecycle.</li><li>Strong problem-solving skills and attention to data integrity.</li><li>Excellent communication skills. </li></ul> Nice to Have <ul><li>Knowledge of FIX protocols, SWIFT messaging, or regulatory reporting frameworks.</li><li>Experience with cloud platforms (AWS, GCP, Azure).</li><li>Familiarity with data pipelines, scheduling tools, or workflow orchestration.</li></ul>

Question	Topic	Difficulty	Ask Chance
Boarding Times Bias	Statistics	Medium	Very High
Decreasing Comments	Product Metrics	Easy	Very High
Hundreds of Hypotheses	Statistics	Medium	Very High

Selby Jennings Interview Questions

Selby Jennings Interview Guides

Selby Jennings Interview Questions

Selby Jennings Opening Jobs