I've been managing a portion of my investments since 2010 and find one of the hardest decisions is when to sell an investment. One rule I follow is if I have a 100% gain, I sell a portion of if. This of course only covers one of many reasons to sell, and taking profits maybe the least stressful reason, but I find this reduces my overall mental load in managing my accounts.
I wanted to share and see what you thought of this idea and see if you, or any other members, have other rules of thumb for selling to help novice investors.
While it is a bit arbitrary, we think selling a bit after a double can make sense for rebalancing purposes. Also, if trimming a little at this stage gives an investor the peace of mind to continue holding on to a portion of that holding, that is probably an even better outcome. At the end of the day, diversification and total portfolio decisions should take priority as you don't want the outcome of an entire portfolio to be driven by a single stock. There are a lot of success stories about concentration but you also don't hear about the failures and holding on to large positions is always easier when things are working.
Overall if the thesis changes, that can be a reason to sell. We prefer not to sell something just becaue 'it has gone up'. However, if it has become too large of a part of a portfolio, then trimming some makes sense.