What the interns have wrought, special jumbo 2026 edition
It’s time again to review some of what Jane Street’s interns built over the summer, though this year we’re going to try to cover more...
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What the SP interns have wrought, 2026 edition
By: Joanna Lu
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Trading off compute for memory with activation checkpointing
The following is part of a series of posts about 2026 summer intern projects—for more, see “What the interns have wrought, special jumbo 2026 edition”...
By: James Somers
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What the TDOE interns have wrought, 2026 edition
The following is part of a series of posts about 2026 summer intern projects—for more, see “What the interns have wrought, special jumbo 2026 edition”...
By: James Somers
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Mitigating memorization in LLMs
The following is part of a series of posts about 2026 summer intern projects – for more, see “What the interns have wrought, special jumbo...
By: James Somers
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Can you use autoregressive diffusion to generate market data?
The following is part of a series of posts about 2026 summer intern projects – for more, see “What the interns have wrought, special jumbo...
By: James Somers
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A study of sequence weighting at scale
TL;DR: We study the scaling laws of data weighting across in-house and open-weight LMs, finding non-monotonic behavior across scales. We vary the weight assigned to...
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Can you design a chip? Announcing the protocol emulator ASIC competition
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Can you reverse engineer an ASIC?
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Using OxCaml to implement type-safe reference counting between OCaml and Python
Jane Street is known for being an OCaml shop, but for years now Python has been our second major programming language, acting as the primary...
By: Nicolas Trangez
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Formal methods and the future of programming
I’ve been telling people for the last 25 years that Jane Street as an organization was just not interested in formal methods.
By: Yaron Minsky
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strace-ui, Bonsai_term, and the TUI renaissance
We’ve always found strace useful but somewhat hard to work with. Its output is often inscrutable, it’s hard to follow subprocesses or threads, and if...
By: James Somers
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Using group theory to explore the space of positional encodings for attention
Attention is a computational primitive at the core of modern language models, allowing internal representations to reference and influence each other. It’s how these models...
By: Alok Puranik
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Can you reverse engineer our neural network?
A lot of “capture-the-flag” style ML puzzles give you a black box neural net, and your job is to figure out what it does. When...
By: Ricson Cheng
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Results from the Advent of FPGA Challenge
At the end of last year, we decided to try something new: a challenge that would run alongside Advent of Code, where we asked the...
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I design with Claude more than Figma now
For a long time I was skeptical of LLMs—whenever I reached for them I was disappointed by the results. Last year I tried Copilot and...
By: Edwin Morris
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Fun with Algebraic Effects - from Toy Examples to Hardcaml Simulations
I recently ported the Hardcaml_step_testbench library, one of the libraries that we use at Jane Street for Hardcaml simulations, from using monads to using algebraic...
By: Fu Yong Quah
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Getting from tested to battle-tested
Testing is an essential part of building reliable software. It’s a form of documentation, a reminder of mistakes of the past, and a boost of...
By: Doug Patti
