They absolutely can. But so can any investor if they believe that the MM's are manipulating a security that you are invested in. I already filed a complaint online with the SEC, as well as other people I am sure. Unless the Feds are monitoring these guys, it would be very difficult to prove that they are doing something illegal (which it "appears" that they have been since around mid September or so) The main problem is that the SEC needs to accept the case first, which in itself is difficult.