It can't be that hard to catch them!
I question how hard it is to tell if these guys are shorting..there must be records of the trades they made...
For instance, for Maxim... that market seller... can probably be documented to have sold 50 million shares net, net, since February... and there are sure to be records of when client sellers like convertible noteholders delivered shares and when selling was done without the shares
and when net short for a day.. they should have to report something... it is more a question of the will to catch them than anything as far as I am aware.
How about if a individual, market maker and all related entities have a short position of 5% or greater they have to report, just like longs and with the same or worse consequences?