Introduction
If you sell an investment because you are happy it has made you a great return and you are thinking it might have started running out of steam, you need to either enjoy your success and buy something with the money, or re-invest in something that will do better.
In other words, it is useful to have a short queue of new funds waiting that you have researched in advance.
Equally, if you find a brilliant new investment opportunity and don’t have a lot of spare cash, you need to decide what to sell to raise the necessary input to the new fund. That could be a failing duffer, but often it will be a success that you need to close off.