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Hudson River Trading (HRT) Interview Guide

Tier 1 HFT
HQ: New York, NY (WTC)

HRT is famous for having the best engineering culture in the industry. They contribute to LLVM, C++, and Linux kernel. If you are a hardcore systems engineer or kernel hacker, this is your dream job.


At a Glance

Compensation

Intern: $22k/month + Benefits
New Grad: $350k - $550k TC (All Cash)

Interviews

Focus: Intense C++ (Templates, Undefined Behavior), Linux Systems, Networking.

Tech Stack

Core: Modern C++ (C++20/23), Python.
Philosophy: "Automate everything."

The Interview Process

  1. CodeSignal / Hackerrank: Standard algos but focused on efficiency.
  2. Phone Screen (C++ Trivia):"What is the difference between `std::vector` and `std::list` in terms of cache locality?" "Explain `virtual` destructors." "What happens when you type `ls` in a terminal?" (Kernel level).
  3. Onsite: 3-5 Rounds.
    Expect to debug a segfault on paper. Expect to write a lock-free queue or explain a specific network protocol (TCP/IP).

Sample Questions

C++: The Vector Resize

You have `std::vector<T>`. You push_back one element and it triggers a resize.
Describe exactly what happens in memory.
(Hint: Allocation, copying/moving elements via move constructors, deallocation of old buffer).

Systems: The Cache Miss

Why is iterating a `std::vector` roughly 100x faster than a `std::list` for large N?
Explain CPU Cache Lines, prefetching, and pointer chasing.

Culture & Perks