[polkaface]

I am pretty sure you want to set a stop order only (as a loss limiting function). Once the stop threshold is crossed it will turn into a market order to get rid of it as fast as you can.

From the FOOL...

For example, if you bought a stock at $20 that is now trading at $50 and you want to sell it if it drops to $40 (locking in a 100% gain), there's a certain kind of order you may want to place -- either a "stop-loss" or "stop-limit" order. The "stop" activates the order if shares sink to a certain price ($40 in your example). The stop-loss order immediately sells the shares at the best price it can, while the stop-limit will sell only if the shares are at $40 or above.

Here are the risks: If, perhaps because of bad news, the shares suddenly fall below $40 overnight and don't rise above that, the stop-loss will sell your shares for less than $40, while the stop-limit order won't sell the shares at all.