I'm not a current employee, but at the time that I was, they did have a small unit who did pseudo-HFT on a prop basis and various electronic market-making busin

I'm not a current employee, but at the time that I was, they did have a small unit who did pseudo-HFT on a prop basis and various electronic market-making businesses, but they were all firewalled off from the people who did brokerage business. We didn't share code or information with them and for obvious reasons they had no ability to view client order flow, unexecuted orders etc. Likewise people in the high-touch (ie voice) execution business couldn't see anything in the GSAT business even though they could use our algos to execute orders if they want to. My understanding (could be incorrect) is that their quant trading business (what they called their 'HFT' shop, although it wasn't really high-frequency compared to real HFTs like Winton, Knight, Jump, Citadel or whatever) was probably going to get shuttered as they moved out of proprietary risk-taking generally, but I don't have any information either way. In GSAT at the time, compared to others on the street our tech was pretty sophisticated intellectually but not fast (eg we didn't have ultrafast marketdata, our exchange latency was quite high and our execution algo speed was pretty slow) and so we had to do a lot of smart coding to prevent ourselves being ripped off by actual HFTs given they could move so much faster than we could. There's a lot more to HFT than reg NMS by the way, I was working in London, so we did all the GSAT trading on European exchanges none of which has anything crazy like reg NMS and there was still HFT shenanigans of various kinds that people would try (eg timing arbitrages if they could see that you had different execution speeds on different venues etc).