TGS is a quantitative investment firm based in Irvine, CA. I found the position through an on-campus job posting. They oddly provided a Gmail account as contact information and did not have a website at the time so they seemed sketchy at first but the people I spoke with were clearly well-qualified so it was just a function of the firm being very secretive. Based on the job posting and speaking with the interviewers, the firm has about 30 "research and software professionals" in their main office in Irvine, CA and they have been around for "over two decades." The interview process was the standard quantitative finance phone interview routine. They took 1-2 weeks between rounds to get back to me and they told me there would be around 3-phone rounds before a fly-out to Irvine. One of the interviewers had been a chemistry professor at UC Irvine before moving to TGS.