I am typically a long term investor, I learnt this from my father. He would buy a share in a company and pretty much hold it forever. This was a very long time ago, and the strategy seemed to work. I tried this a few years back, and noticed it worked for your typically blue chip stocks, because after a big correction, or even a crash they seemed to recover. But it seems these days there is always a time to sell, and knowing when to sell is more important than actually buying the share.
Perhaps this is because there is a lot more data available these days to see trends, and identify when stocks have run their course. Many people use the 50, 150, or 200 MA to get an idea if a stock has run its course, and make it a hard rule to exit a position if it does not hold one of these key levels.
What do you folk all do with your portfolios? Do you watch the fundamentals or exit on a technical break of structure or a combination of both?