I assume you mean Renaissance Technologies. I categorise it as pure HFT. They are not taking long-short technical or macro positions in their main fund -- that I know. (Others: Please correct me if they have other funds, or changed strategies in last few years.)

That said, RenTech was under intense scrutiny by SEC and IRS for their incredibly aggressive tax strategy. I did not follow it to the end.

Medallion fund? I thought it was stat-arb.

Interesting point/question.

First: Yes, Medallion fund is the primary fund of RenTech.

Second: To me, stat-arb can be HFT or non-HFT. They were/are doing HFT stat-arb in Medallion fund. AQR, Virtu, and Citadel are probably doing both HFT and non-HFT stat-arb. Twenty years ago stat-arb was called "pairs trading". Today, it is much more complex: basket vs basket.