Just spent way too long diving into Jane Street and honestly, this company is absolutely wild. Like, I knew they were big in trading, but the depth of what they actually do is mind-bending.

So here's the thing—Jane Street started in 1999 with four guys in a tiny windowless office doing ADR arbitrage. Sounds boring as hell, right? But then they made this bet on ETFs when nobody cared about them, and it basically changed everything. Fast forward to 2024, and they pulled in $20.5 billion in net trading income. That's more than Citigroup ($19.8B) and Bank of America ($18.8B) combined, except they did it with just 3,000 employees. Citibank has 220,000 people. The efficiency gap is actually insane.

What really gets me is their culture. No CEO. Like literally no CEO. Around 40 senior people just make decisions collectively. They use OCaml (a programming language almost nobody else uses) as their core trading system—25 million lines of code. Their interview process is basically all probability puzzles and game theory problems. They don't care if you know finance; they just want to see if you can solve weird shit under pressure. And they don't use non-compete agreements, which is unheard of in finance.

But here's where it gets dark. Jane Street has been involved in some seriously questionable situations. The SEBI (Indian Securities Exchange) basically caught them running what looks like market manipulation on Bank Nifty options. The pattern is wild: they'd buy massive amounts of stocks and futures in the morning, then sell everything in the afternoon to artificially tank the index and profit from their short options positions. SEBI's report showed that on one particular day, they lost $7.5M on spot trading but made $89M on options—net profit $81.5M. From January 2023 to March 2025, they made about $4 billion total in India, with most of it coming from options while they actually lost money on futures.

Then there's the Terra/Luna situation. The lawsuit claims that Jane Street had an insider at Terraform (an ex-intern named Bryce Pratt) who tipped them off. On May 7, 2022, Terraform quietly withdrew $150M of UST from Curve. Ten minutes later, Jane Street withdrew $85M from the same pool. They basically helped drain the liquidity that was holding up UST, then watched it collapse. After the ecosystem started dying, Pratt supposedly messaged the Terraform team suggesting they buy Luna at a discount. Move the valuables out during the fire, then offer to buy the ashes cheap.

And SBF? Yeah, he worked at Jane Street from 2014-2017. Made $300K in year one, $600K in year two, then a $1M bonus in year three. During the 2016 election, he built a system to predict voting results faster than CNN so Jane Street could trade before anyone else. They shorted the market hard thinking Trump's election would crash stocks. They were up $300M at one point, then the market rallied instead. Turned into a $300M loss overnight. But they didn't fire him—they actually praised the accuracy of his forecasting system. The problem was just his market judgment call, not the math.

The whole Caroline Ellison connection is there too. She was an Alameda CEO and also came from Jane Street. Same with Gabe Bankman-Fried (SBF's brother), and a bunch of other people who later founded Modulo Capital. The density of Jane Street alumni in the FTX disaster is impossible to ignore.

What's fascinating is that Jane Street operates in this weird gray zone. They're technically not doing anything illegal in most cases—they're just using information asymmetry and speed in ways that feel... aggressive. They describe themselves as "puzzle solvers," and they literally have an Enigma machine in their office as decoration. The message is pretty clear: we love encryption, secrecy, and building systems that only we understand.

The 2024 Q2 numbers are even crazier than 2024 full year. They hit $10.1B in just three months in 2025, and their first three quarters of 2025 totaled $24B. That's already more than their entire 2024 revenue.

I think what makes Jane Street so interesting—and honestly unsettling—is that they've basically built a machine that exploits every possible edge in financial markets. They're not breaking rules exactly, but they're definitely testing their boundaries. They're the company that barely anyone knows about until they end up in a lawsuit. And by then, they've already made billions.

The real question is whether this is just extremely sophisticated trading, or whether it's something darker. Maybe both. Maybe that's the whole point.