I think the big issue with the 211 is that any market maker is taking a risk by trading them. If they were fully reporting and there is a suspicion of fraud then the MMs would want to satisfy themselves that the filings themselves weren't fraudulent. That could involve a lot of time and independent accounting. I think that's one of the big hurdles - the MMs have plenty of other fish in the sea, why take a risk or go to a big effort to evaluate the risk?