Varadh

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.

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 function– 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 2°C. 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 Street– 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.

We stealth-churned off Notion months ago. We didn't realize it. We didn't tell Notion. It's just ... our agents have no need for it. They're doing the work now. Stealth churn is the under-discussed agent risk. Usage drops to zero quietly. The renewal email never even goes out.

We stealth-churned off Notion months ago. We didn't realize it. We didn't tell Notion. It's just ... our agents have no need for it. They're doing the work now. Stealth churn is the under-discussed agent risk. Usage drops to zero quietly. The renewal email never even goes out.

yall mind if i post some claudeslop in a sec been finding opus 4.7 very very fun to talk about research with, and almost-good at technical research writing with a few revision passes realistically this is prob the only way i get longform tech blogs written consistently lol