No harm done - can be rewarding nonetheless.

My example:  I have a parallel example with a tech stock that has been under appreciated for so long, I know the company inside out, believe it will take off, and have held for a long time an overweight position.  So just a couple of months ago I decide to let go of some substantial holdings because it was so "boring" and 'taking so long' and thought to follow the action elsewhere. 

So my new US biotech takes off and I am killing it (soon to take some profits) but low and behold shorly after my sell, my goofball tech stock starts to take off as well, pre-releases spectacular earnings, and institutions back in to run volume up as other developments emerge.  Oh man! 

So lucky I re-positioned into a good choice (the relative gains comparable or greater with the new investment), but ain't it always this way. The irony was that a long term hold wasn't hitting my expectations until a month after I sold half my position!!