Doubling Up
Doubling up has destroyed more traders than any other trading strategy. When a trade moves against me, I look to get out of it, not add to it. I know an individual trader who kept adding to his Micron Technologies position as it dropped from 85 to 20. It will be years before he ever possibly breaks even. Thank you, but no thank you. When a position moves against you–get out!
–from Hit and Run Trading by Jeff Cooper