Seconded. I think generally people give way too little weight to actually doing things well. There can be some clever mathematical ideas in there here and there

Seconded. I think generally people give way too little weight to actually doing things well. There can be some clever mathematical ideas in there here and there, but in the end it has to come together into a running organization that makes little mistakes and can run consistently (while also observing a lot regulations). For me the "spooky magic" is more the ability to pull this off in size. Edit: I do have friends on the buy side that use pretty fancy models, but those places are not in the HFT/market making game. But using those models does not take away from needing to be able to translate the edge consistently and efficiently.