Buying and holding is a tried and true investing standard.
But that doesn't mean there isn't a good reason to sell a stock in your portfolio.
From Rex Moore at the Motley Fool.com, consider these signs that it's time to sell:
Selfish management. If the executive team starts worrying more about lining its own pockets than about creating value with the business, it's time to let go. For clues, keep an eye on excessive compensation, and active insider selling.
Competitive disadvantages. PepsiCo prices its products higher than competitors because consumers will pay more for a Pepsi. If your company is facing weak pricing power, a declining customer base and lower market share, it's probably operating at a competitive disadvantage.
An unstable financial model. eBay and 3M are known for stable or rising margins and steadily increasing sales. Companies heading in the other direction are showing a red flag.