You can do block trades in it with a designated counterparty if you don't want any execution risk - some of said counterparties are market markers in it.
Additionally there's plenty of traders, both human and algorithmic, who are there trying to capture the spread.
However, there are no privileges as such for being a market maker, anyone can do what they do.
There *may* be a designated market maker scheme as well, but I don't think so.