Quote from steve.larson:
Forget about Datek's horrible customer service, and D.I.Y.S. Go to your "trading home" page on datek.com. Click "rapid order entry" in the lower right corner. Do this outside regular market hours. In your rapid order window enter "b100ibm t80%" (without the quotes). Translation: buy 100 IBM at market, and then sell the same at market if price drops $20%. See how easy this is? Alternatively, in your rapid order window enter "b100ibm t10" (without the quotes). Translation: buy 100 IBM at market, and then sell the same at market if price drops $10.