It is not specific to Block Positions, it just so happens that the particular Broker in the OTC that represents a Customer with their Block Position deems it necessary to not adsorb the Regulatory Fee for such transactions, much of this has to do with dollar volume. Nobody wants to fess up as to who is exactly passing the fee along as if if they would be divulging PI about the particular account or something.
However it could be assessed to buying retail if the Broker Dealer doesn't want to pay it either and passes it on to the buying party.
I dont know how many brokers are doing so, but I do know one in particular that represents Block Positions are in fact doing so.
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