[dclusin]

You are absolutely correct on the price they get for them being dependent on how they are sold. The industry jargon for this is how you execute the buy or sell. One option is they could sell the bitcoins using a VWAP algorithm.

http://en.wikipedia.org/wiki/Volume-weighted_average_price

For all other asset classes VWAP execution is a thing and a common one at that. Basic idea is split your large order up into slices and sell small amounts during a given interval. Bitstamp & BTCE have 24 hour volume of ~18k bitcoins. As a fun aside, if you don't randomize your time slice someone like me will see what you're doing and move the market to screw you :).