You are right Echilen. If you commit your shares then the brokerage has to be able to have them at hand and they can't short them. Otherwise the brokerage can make your shares available to short traders. The MM is allowed to trade naked shorts to provide market liquidity, and they often do especially with stock that don't normally have a lot of volume. You can set a price as high as you want as long as the brokerage allows it. You can cancel at anytime you want to sell..
I don't know for sure either way but I have read on various different message boards that locking your shares up at high sell prices protects them from being borrowed for shorting.
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