When to buy:
1. The underlying company is great
2. It is selling for much less than it is worth
3. Consistently high profitability
4. Low debt levels
5. Able to pay its short-term obligations
6. Has a durable competitive advantage
7. When it's current stock price is at least 25% lower than its intrinsic value.
When to sell:
1. Price reaches value.
2. Long-term problems arise
3. A better opportunity becomes available.
The wisest rule in investment is: when others are selling, buy. When others are buying, sell. Usually, of course, we do the opposite. When everyone else is buying, we assume they know something we don't, so we buy. Then people start selling, panic sets in, and we sell too.