When to sell a single stock to lock in gains

[Proud Foot]

I have a single stock holding that has increased in price since I bought it and if I were to sell it now it would give me approximately a 20% gain.  I am not selling because it still meets my buy and hold criteria but it has made me think about my IPS and how I should determine my sell decisions for reasons other than no longer meeting my buy and hold criteria.  I also believe this stock will continue to appreciate in value.

So my question then is how do those of you who buy single stocks decide when to sell and lock in gains?

[tarheeldan]

trailing stop. limit your losses but let your gains run.

[neo von retorch]

It sounds like the only reason you'd sell a stock you believe in under a buy and hold system would be a) you need the money and this is in asset class that you're overly heavy in or, similarly b) there is an investment you're confident is better.

[YoungInvestor]

It sounds like the only reason you'd sell a stock you believe in under a buy and hold system would be a) you need the money and this is in asset class that you're overly heavy in or, similarly b) there is an investment you're confident is better.

In b) you should also add that the other investment appears better, after accounting for the tax implications.

[forummm]

Or if your opinion on the stock changes (such as you believe it's overvalued or the firm is now riskier than you thought, etc).

[Proud Foot]

Those are the responses I thought I would get.  When I buy stocks, I buy with the intent to hold forever.  I do not think it is the best idea to buy and forget so I review my positions quarterly to see if my opinion on the stock has changed.  I will evaluate more frequently if significant news about the company is announced.  The last thing I want to do is to be stuck holding onto worthless stock.