Staff Machine Learning Engineer

Responsibilities

• Build, evaluate, and maintain underwriting and decisioning models across Cash App Borrow and Afterpay
• Design and evolve credit decision frameworks, including modeling, automation, and policy logic
• Design and run experiments to evaluate model performance and impact on approval rates and loss
• Develop deep understanding of borrower behavior and repayment dynamics to inform model design
• Work across the full modeling lifecycle: problem formulation, feature engineering, training, calibration, deployment, and monitoring
• Build agentic engineering workflows to accelerate development, testing, and documentation
• Collaborate with Product, Engineering, Legal, Compliance, and Operations teams
• Shape how AI developer tooling is adopted across the team

Requirements

• Bachelor's degree in a quantitative field (Mathematics, Statistics, Physics, Computer Science) or advanced degree
• 10+ years applying AI, machine learning, or statistical modeling in decisioning contexts (credit, risk, fraud, etc.)
• Experience with probabilistic models and decision systems, including calibration and score transformations
• Strong experimentation skills including designing holdouts and measuring lift
• Experience with model monitoring, degradation detection, and retraining strategies in production
• Proficiency with AI-native development workflows using LLMs and agentic coding tools
• Experience explaining modeling concepts and limitations to senior stakeholders

About the Company

Block builds technology to increase access to the global economy. Across our ecosystem, including Square and Cash App, we create tools that help businesses run and grow, and individuals move, manage, and grow their money with confidence.