Net Interest

Net Interest

Crossing the Rubicon

Jane Street's Journey from Shadow to Spotlight

Marc Rubinstein
Sep 05, 2025
∙ Paid
56
Share

Happy Friday everyone. I hope you had a good summer. I did a Grand Tour of Europe, visiting Berlin, Prague, Vienna, Ljubljana, Zagreb, Sarajevo and many of the lakes, mountains and coastal regions in between. If you’re visiting any of these places and want some tips, drop me a line.

Although writing took a break while I was travelling, podcasts continued for paid subscribers. In case you missed them, I spoke with Huw van Steenis about private credit, Ben Hunt on market narratives and Tim Levene on fintech investing. Next week I’ll be releasing an episode with Tom Hayes, the trader imprisoned over the LIBOR scandal whose conviction was recently overturned. To access it, be sure to subscribe here.

For now, though, it’s back to our regular Friday programming. One firm I’ve been thinking a lot about lately is Jane Street. It came under the spotlight a few years ago after the publication of Michael Lewis’s book, Going Infinite: “By 2014, when Sam started as a full-time trader at Jane Street Capital, the financial institutions at the center of markets – those setting the prices of global assets – were not the old investment banks but opaque high frequency trading firms, like Jane Street, that basically no one had ever heard of,” he writes. Lewis later admitted that he started talking to Sam Bankman-Fried partly as a means to get access to Jane Street, about which he dedicates two chapters of his book. “The sums of money made by the people who ran these places were orders of magnitude greater than what the people who ran the big investment banks had ever made.”

These days, Jane Street is hard to ignore. In the second quarter of this year, it generated $10.1 billion of net trading revenue, taking its total for the first six months to $17.3 billion. That’s more than Goldman Sachs earned in trading ($16.4 billion) and almost as much as JPMorgan ($18.6 billion). With 3,000 staff, it translates into $11.5 million of annualised revenue per employee – significantly more than those two investment banks, and more than almost all technology companies with the exception of high-rent network monopolies such as OnlyFans and Valve.

Jane Street’s strong performance shows up in other metrics, too. Its profit margin in the second quarter was 68%, which compares with 32% at JPMorgan and Goldman Sachs (although theirs includes advisory activities and prime brokerage). And its return on equity annualised at over 90% based on end-2024 equity – a number few regulated firms are able to match. As a case study in scalability across both capital and technology, Jane Street is hard to beat.

A few years ago, Jane Street was utterly opaque. “You couldn’t just google ‘Jane Street Capital’ and learn anything useful about the place,” writes Michael Lewis. “There was hardly anything about Jane Street Capital on the internet.” As it has scaled, that’s changed. The firm now provides a pathfinder for prospective recruits and releases financial information to its private bondholders. Although staff turnover remains low (at just 6% over the past two years) more and more ex-Jane Streeters are emerging from the 25-year-old firm to divulge what goes on. Its recent spat with Indian securities regulators adds further color, shedding light on specific trades to reveal some of the ways Jane Street is able to make so much money.

To explore further, read on.

This post is for paid subscribers

Already a paid subscriber? Sign in
© 2025 Marc Rubinstein
Privacy ∙ Terms ∙ Collection notice
Start writingGet the app
Substack is the home for great culture