As of my involvement in high end HFT firms a few years ago no one was yet doing ASICS and the state of the art was FPGA. I would say people have a mythology about HFT that’s both deserved and overblown. They tend to be very sophisticated in many ways, but also surprisingly immature. Likely because they’re so private and insular, and grew up very non traditionally. They’re often also long term participants so their stacks are fairly aged at this point. Most of their advantage is the barrier to entry is high.
I know of a few places actively looking into ASICs/hiring xilinx/intel/amd hw engineers to work on them, but from what I can tell the majority just use FPGAs.
