[sseveran]

These are wildly different businesses. Virtu is a global electronic market maker which in reality is more like a mature technology company than a risk taking hedge fund. Renaissance (Medallion specifically) is a weird fund that manages employee money. Citadel is a large, diversified financial services company that happens to have overlap with both of the previously mentioned firms. They have a large market making operation and offer a variety of different hedge funds that they market