Cat, and all,
In this, and any stock, a "market" order just clears out the bid, and if large enough, the limit bids below. By definition, the stock sells off in price!
In addition, one never knows what one will get with a "market" order. We saw that with the .01 sell prices last April on previously $30 stocks on that "flash crash". Again, the seller gets a poor price for a speedy execution, and the rest of the longs suffer. A "market" order is the hallmark of panic selling, and is essentially a selfish "me first" action that shows a lack of caring about the impact on other investors.
Selling via the use of limit orders at the asked, or above the asked, allows the seller to get out without impacting the share price. True, such orders load the stock with supply. As such, they slow the advance of the share price, but at least they don't result in negative price action.
I urge people here who are long and who want some of their money out to use limit orders, placed on the asked, or above. Such is a way to sell, and not ruin the share price for all.
Think about it - Tomcat