I've notice this with MXXR and other stocks. Sometimes, eg. when I buy thru my broker, they will split a large block into small units (even 5,000 shs) and still charge me $9.95 for the whole lot. I have seen, for example, a purchase of 200,000 shs be broken up into small units, 10,000, 75,000, etc. and go thru at different trading times. They will even purchase some of the lots cheaper than my purchase price limit. However, the total commission is still $9.95 for everything. Maybe that is what happened here.
Charlie
Williamsburg, Va