Over 700 finance terms, Shmooped to perfection.
A no-no. A market maker offers to buy 100,000 shares of MSFT from you at $26.12 - then says "um, no". That's an NASD violation. In practice, trading is done among generally trusted and known parties so if a player backs away from trades, the rest of the field simply stops doing business with them and they wither and die.