Senior Quantitative Researcher

Petra Security•San Francisco, CA

2d•Onsite

About The Position

Petra is building an AI-driven Detection and Response platform to catch and remove attackers before they can act. The company has experienced rapid growth, reaching mid-7-figures in ARR in under a year and doubling ARR in the past few months, now protecting over 2.5 million users across 10,000+ businesses. This role offers a rare opportunity to join early and help scale the company to over $30M in revenue in the next 12 months.

Requirements

5+ years of quantitative/machine learning research experience.
Meaningful time designing, training, evaluating, and shipping models in production systems at scale.
Strong quantitative fundamentals: probability & statistics, linear algebra, linear and non-linear modeling, NLP.
Experience training & deploying models in production.
Strong engineering fundamentals — write clean, production-grade code.
Comfortable owning a system end to end, not just the modeling layer.
Experience working with real-time or streaming data pipelines, feature stores, high-performance databases, and distributed systems.
High agency and high output: identify problems, propose solutions, and execute.
Learn fast, ask the right questions, and figure things out.
Ship fast and find the 90/10.
Comfortable in a small-team, high-autonomy environment.
Proud of your craft and care about building things that work well and hold up over time.

Nice To Haves

Experience in high-stakes domains like quantitative finance or fraud detection.

Responsibilities

Build and evolve our detection models.
Design and build ML models that identify account compromise in real time.
Take models from research to production.
Measure how models behave at scale in a live system with real attackers.
Architect and implement solutions that handle significant increases in scale.
Establish patterns, push for correctness, and raise the quality of the team's work.