Had a Jane Street phone interview in 2016. "Price a 6-month forward on carrots."
There's no carrot futures market, so I build one from scratch: seasonal harvest cycles, USDA demand elasticity, cold storage decay rates.
One trader stops me. "Your storage cost functionโ you're modeling the carrot as dead inventory. Like grain in a silo." He asks me the metabolic respiration rate of a post-harvest carrot at 2ยฐC. I estimate.
"Your forward is overpriced by exactly that shrinkage. The underlying is consuming its own sugars. It's alive." Good correction. I adjust the model. I think I've recovered.
Rejection email comes the next morning. Subject: "Ethical Review." My framework, they write, "relied on the severance of the root organism from its growth medium." The question about respiration was a test. The carrot was still alive and I'd built an entire derivatives structure on top of its death without questioning whether harvest was an acceptable act.
I pull up the recruiter's original email. It doesn't say Jane Street. It says Jain Streetโ a non-violent quantitative commodities fund.
The carrot was never supposed to be priced. It was supposed to be refused. I later learn the only candidate who passed that round was a former monk from Gujarat who sat in silence for eleven minutes and said, "I cannot put a price on life." He's now a partner.
Jane Street made ~$40B in 2025 with 3,500 employees, a ~2x from the year before.
At ~65-70% profit margin, that's $8M profit / employee, the highest for a 1000 ppl company. High-frequency trading continues to be the most efficient money making engine.
I want to share an old story about my Jane Street interview in 2014. Jane Street was known for hiring a lot of math, physics and CS olympiad winners from top universities and putting them through many rounds - including, for trading roles, a gauntlet of mental math. It was my 6th interview and my final round and I recall being asked "What is the next day after today in DD/MM/YYYY where all the digits are unique?" They'd toy with you and say "You can use a pencil and paper, if you want" but you knew that was an instant no. Painstakingly and as quickly as I could, I came to an answer. "How confident are you that this is correct on a 0-1 probability scale?" the interviewer said. "0.95", I blurted out, not fully knowing how to answer that. "Are you sure?" After thinking harder for a few more seconds, I realized I could've flipped the digits around to get a closer date. I gave the interviewer my answer. It was correct. "0.95 huh?" he chuckled. That's when I knew I failed.
Note: fwiw, other companies that come close in efficiency are
- Tether ($90M profit/emp)
- Hyperliquid ($80M profit/emp)
and on revenue:
- Valve ($50M/emp)
- OnlyFans ($37M/emp)
- Craigslist ($14M/emp)
- Anthropic ($12M/emp, run rate)
- OpenAI ($8M/emp, run rate)
For comparison, Nvidia is very efficient at scale and is $4.4M/emp.