[lelandfe]

Two Sigma is notoriously tightlipped about everything. This guy's short post about interning there in 2015 is probably the most I've even seen about working there: https://evjang.com/2015/08/17/internship-experiences.html

[kyawzazaw]

In terms of "tightlippness", they don't come close to TGS Mgmt. All of their employees can't even list their employment at TGS Mgmt on LinkedIn.

[oogali]

I worked at a firm who had the same policy in 2014.

It was more common than you may have realized.

[Mandatum]

Honestly, most boutique, government-involved security consulting firms have similar requirements. Given how much of tech is outsourced these days, obscurity is often the only line of defense some organisations have.

[marricks]

So smart stock trading. Cool. The best and brightest are off solving math problems to make bank in the stock market.