Hefu Chai
Hefu Chai (born c. 1990) is a software engineer based in Menlo Park, California, who spent much of his career building consumer technology and cryptocurrency infrastructure at Robinhood, Facebook, and OpenAI. On 15 September 2026, U.S. federal prosecutors charged the 36-year-old Chai with commodities fraud and wire fraud, alleging that while employed at Robinhood he misappropriated confidential information about upcoming cryptocurrency listings and used it to trade perpetual futures on the decentralized derivatives exchange Hyperliquid ahead of the company's public announcements.[1][2]
Before the charges, Chai had built a career spanning roughly eleven years across financial technology, social media infrastructure, and artificial intelligence, including a five-year tenure at Robinhood where he led the launch of several of its crypto products.[3]
Early Life and Education
Chai completed his undergraduate studies at Shanghai Jiao Tong University in China, where he earned a Bachelor's degree with a major in Computer Software Engineering and a minor in Finance. During his time there he received several academic distinctions, including the National Scholarship of China awarded by the Chinese Education Ministry in November 2011, in which he ranked 4th out of 170, and two Scholarships of Academic Excellence from Shanghai Jiao Tong University, awarded in November 2010 and November 2012.[3]
He subsequently pursued a Master's degree at the School of Computer Science at Carnegie Mellon University in Pittsburgh, Pennsylvania. His graduate coursework concentrated on data systems, distributed computing, and machine learning, spanning subjects such as advanced storage systems, database systems, parallel computer architecture, and multimedia databases and data mining.[3]
Research and Technical Work
While at Carnegie Mellon, Chai worked on a series of systems and machine-learning projects. He built a simplified MapReduce framework and distributed file system inspired by Hadoop, supporting file replication, fault tolerance, and failure recovery, and constructed a hybrid storage system using the FUSE toolkit that combined SSD performance with cloud-storage capacity through segment-level deduplication, compression, and caching. His work on GPU computing included accelerating backpropagation through time for training LSTM neural networks using the CUDA Thrust and CUBLAS libraries, which he reported achieved a 20-fold speedup over a Matlab CPU implementation. Other projects covered graph mining across big-data systems such as HP Vertica, Hadoop, Apache Hama, SciDB, and PostgreSQL, the rewriting of graph algorithms including PageRank, triangle counting, and belief propagation in plain SQL, and research on load balancing of the Bulk Synchronous Parallel model in multi-core environments.[3]
Chai also presented a talk titled "Invisible loading: Access-Driven Data Transfer from Raw Files into Database Systems," which examined how to reduce the "time-to-first-analysis" for large scientific and social-network datasets. The presentation described a technique for incrementally loading data into a database system as a side effect of running MapReduce jobs over a distributed file system, with the goal of combining Hadoop's low startup cost with the long-term query performance of a database. Building on ideas from HadoopDB and using components such as HDFS and MonetDB, the design he described loaded only the attributes actually processed by a job, used address columns to track tuple movement during sorting, and employed an "incremental merge sort" approach intended to keep query effort bounded. Chai reported that the method imposed almost no burden on MapReduce jobs and offered relatively low cumulative cost, while noting weaknesses such as data duplication without garbage collection and suitability mainly for short-lived data.[4]
Career
Morgan Stanley and Google
Chai's early roles were brief. He worked as a software engineer at Morgan Stanley in Shanghai in 2012, in Technology and Information Risk, and later as a software engineer at Google in Mountain View, California, where he worked on the AdWords serving infrastructure within its advertising business.[3]
From January 2015 to January 2021, Chai was a Staff Software Engineer at Facebook, based in Menlo Park, California, working on Instagram Infrastructure and Messenger. According to his own account, he led and built a self-serve platform for demand and efficiency across web, machine-learning, caching, and storage systems. On Messenger he led development of the product's first version of ephemeral messaging features and its in-app games, contributed to modernizing the Messenger camera for augmented reality, and helped enable branded AR effects.[3]
Robinhood
Chai joined the brokerage firm Robinhood in January 2021 as a Senior Staff Software Engineer, a position he held for five years until January 2026. He states that he led the development and launch of several of the company's cryptocurrency products, including perpetual futures, crypto staking, and Robinhood Connect, a crypto on
- and off-ramp. He also states that he scaled the company's crypto trading systems through database and service sharding to support growth and reliability, started an engineering design and severity-event (SEV) review program to improve engineering quality across the organization, and bootstrapped and grew the team responsible for the crypto trading experience, including the launch of the crypto tab.[3] This tenure placed Chai at the center of Robinhood's crypto listing operations, the confidential knowledge of which later formed the basis of the insider-trading charges against him.
OpenAI
In June 2026, after leaving Robinhood, Chai joined OpenAI as a Member of Technical Staff, based in the San Francisco Bay Area and affiliated with the company's Codex product, an AI coding tool.[3] Working on the openai/codex repository, he is reported to have developed a backend feature enabling real-time querying of the pairing status of remote control devices, implemented as a status transport layer written in Rust and TypeScript with an experimental gRPC-based endpoint. The feature allowed the desktop application to poll pairing status using either a pairing code or manual entry, establishing an end-to-end status flow between the backend and the desktop app that is reported to have improved onboarding reliability.[5]
Hyperliquid Insider Trading Case
On Tuesday, 15 September 2026, the U.S. Department of Justice announced charges against Chai and a co-defendant, Huaisong Xiang, a 30-year-old Robinhood engineer from Jersey City, New Jersey. Each was charged with one count of violating the Commodity Exchange Act, which carries a maximum sentence of ten years in prison, and one count of wire fraud, which carries a maximum sentence of twenty years.[1][6]
Prosecutors allege that between 2025 and 2026, Chai and Xiang had access to nonpublic information about whether and when Robinhood Crypto planned to add particular cryptocurrencies to its trading platform, and that they repeatedly purchased perpetual futures tied to those tokens on Hyperliquid before Robinhood publicly announced the listings. According to the government, each man profited more than $50,000 from the trades.[2][6] A distinguishing feature of the case is that the indictment alleges trading in perpetual futures — derivative contracts — rather than in the underlying tokens themselves, which sets it apart from a 2022 Justice Department prosecution over advance knowledge of Coinbase token listings that the department had called the first cryptocurrency insider-trading tipping scheme.[1]
Jamie McDonald, the U.S. Attorney for the Southern District of New York, stated: "Misappropriating confidential information to trade in the derivatives markets for personal benefit is illegal," adding that the charges make clear that corporate insiders cannot evade the securities and commodities laws by trading based on misappropriated information in derivatives such as perpetual futures, tokenized securities, or other similar financial instruments.[2][1] The case was investigated by the FBI and is being prosecuted by the Securities and Commodities Fraud Task Force of the U.S. Attorney's Office for the Southern District of New York.[2]
Chai was scheduled to appear the same day in federal court in the Northern District of California, while Xiang was scheduled to appear in Manhattan federal court. The charges are accusations, and both defendants are presumed innocent unless and until proven guilty.[2][6]
