The Most Important Firm You’ve Never Heard Of - Part 1

In 2025, one trading firm pulled in $39.6 billion in net trading revenue. That's 11% more than JPMorgan. It's more than Goldman Sachs. It's more than Morgan Stanley's entire markets division. The firm did it with roughly 3,500 employees. JPMorgan has more than 300,000.

Most readers can name JPMorgan's CEO. Almost nobody outside the industry can name a single person at this firm. There isn't a CEO to name. The firm doesn't advertise. It doesn't do interviews. Its founders are mostly gone. Its current leadership operates, by its own former employees' description, more like an anarchist commune than a Wall Street firm.

This is Jane Street. And once you understand what it's become, you start to see why its absence from public conversation is the most interesting thing about it.

From a Susquehanna Spinoff to a Superpower

Jane Street was founded in 1999 by four people: Tim Reynolds, Robert Granieri, Michael Jenkins, and Marc Gerstein. The first three came from Susquehanna International Group, the Philadelphia options shop run by Jeff Yass. Gerstein was a developer at IBM. Susquehanna sued them for poaching talent with proprietary information when they left. The lawsuit went dormant. The four moved to lower Manhattan and started trading American depositary receipts (ADRs) on the old American Stock Exchange. ADRs are US-listed certificates that represent shares of foreign companies. The margins were thin. The products were boring. Almost nobody else wanted to be there. That last part mattered.

By the mid-2000s, Jane Street moved into the product that would define it: ETFs. To create or redeem ETF shares, an exchange needs participants called authorized participants (APs) who can swap baskets of underlying securities for ETF units and back again. Jane Street became one of the most active APs in the US. The firm grew alongside the ETF boom, and as ETFs grew from a niche product into the dominant retail and institutional vehicle, Jane Street grew with them.

Today, the numbers are difficult to overstate. By 2024, Jane Street accounted for 41% of bond ETF trading volume globally and held 24% of the primary market for US-listed ETFs. Its average monthly equity trading volume was around $2 trillion. It was responsible for roughly 8% of total US options volume and over 10% of North American equity volume. If you've ever bought or sold an ETF, the counterparty was probably Jane Street.

Of the four founders, only Granieri remains. Reynolds left in 2012 and reportedly went on to build art schools and private resorts. Jenkins left to focus on political donations. The firm has no CEO and reportedly never has. It is informally run by a group of between 30 and 40 senior executives. Compensation is pooled. Most traders don't know their individual PnL. There are no non-compete agreements.

How They Actually Make Money

Jane Street is a market maker. The simple version: it stands ready to buy and sell across thousands of products at all times, capturing tiny spreads on enormous volume. The complicated version is what's made the firm what it is.

It runs proprietary pricing models across ETFs, equities, options, bonds, commodities, FX, and crypto. It writes most of its software in OCaml, an academic functional programming language that almost no other Wall Street firm uses. It builds its own infrastructure. It interviews candidates with probability puzzles, not finance questions. It hires from MIT and Harvard and Princeton, often into multi-year intern pipelines, and almost never hires senior people from the outside.

The shift in recent years has been from arbitrage-heavy strategies into a full-stack quantitative operation that's leaning hard into machine learning. In April 2026, Jane Street committed approximately $6 billion to use CoreWeave's AI cloud platform, including access to Nvidia's Vera Rubin chips. The same announcement included a $1 billion equity investment in CoreWeave at $109 per share.

Jane Street's description of itself in that announcement is worth pausing on: a firm "training large, complex models on massive volumes of noisy data, refining them continuously, and deploying at a scale to help make markets more efficient." CoreWeave's SVP of Revenue called it a firm that "operates like a frontier lab."

That framing isn't marketing. Jane Street is also, quietly, a venture investor. It holds a stake in Anthropic that reportedly gained over $800 million in value in Q3 2024 alone. The CoreWeave equity stake is now $1 billion. As of May 2026, regulatory filings show Jane Street entities also hold 5.8% of Terawulf, the AI infrastructure miner, with 27.7 million shares disclosed across multiple Jane Street subsidiaries.

It is not just a trading firm anymore. It's a quantitative research operation, a venture investor, an AI compute buyer, and one of the largest counterparties in global ETF and derivatives markets, all rolled into one privately held partnership. There isn't really a category for it.

Come back tomorrow for Part 2 of this topic!

*This article is for informational and educational purposes only. It is not investment advice, a recommendation, or a solicitation to buy or sell any security. All allegations referenced in this article remain subject to ongoing legal and regulatory proceedings. Arbitrage Trade has no affiliation with Jane Street Group, LLC or any of its entities.