David Li

Research @ xAI | Ex-Quant @ Five Rings, Jane Street | CS @ Caltech

New York City Metropolitan Area

About

Experience

  • Member of Technical Staff at xAI
    Jan 2026 - Present · 7 mos

    Coding RL Bigrun + RL Science team: core contributor to Grok 4.5 Previously worked on Forecasting: achieved SOTA

  • Quantitative Trader at Five Rings
    2024 - 2026 · 2 yrs

    Buy low sell high and research new strategies to do so.

  • Caltech (5 mos)
    • LLM Researcher
      Mar 2024 - Jul 2024 · 5 mos

      Researched and enhanced LLMs ability to generate correct code for competitive programming problems

    • Research Economist in Utility Theory
      Mar 2024 - Jun 2024 · 4 mos

      Found stronger mathematical guarantees for utility functions that generate an S-shaped convexity in the positive outcome of a weighted flip after paying the theoretical fair bid price. Constructed counterexamples that proved previous conditions for S-shaped convexities were too weak (necessary but not sufficient)

  • Caltech (1 yr 5 mos)
    • Deep Learning Researcher
      Jan 2023 - May 2023 · 5 mos

      Quantified robustness of Fourier Neural Operators for PDEs by adding pixel-wise noise during testing. Improved robustness through data augmentation, noise training, and stability training. Decreased test error and enhanced robustness of FNO on the 2D steady-state Darcy Flow dataset by 35%.

    • Machine Learning Researcher
      Jan 2022 - Jan 2023 · 1 yr 1 mo

      Developed ML method extending on mixed-effects random forests and fuzzy forests to deal with longitudinal high-dimensional data that are both highly correlated through time and data features.

  • Quantitative Trader at Jane Street
    2023 - 2023 · Less than a year

    Worked on the Equities (StatArb) and Options desks, modeling future volume, customer flow, and returns using TRF data, and built forward volatility term structure curves for commodity futures.