A falling price is not the same thing as a cheap stock. A stock that has dropped 30% can still be overvalued, that's often exactly what's happening when the drop is the market catching up to a valuation that was already stretched, or reacting to a genuine structural change in the business, like a fading moat, a shrinking market, or a broken growth story. But a 30% drop doesn't always mean anything changed about the business at all. Sometimes it's simply Mr. Market overreactin

Most investors analyze a stock backwards. They start with the price chart, then the growth story, then — if there's time left — a glance at the balance sheet. By the time they get around to asking "can I actually trust these numbers?", they've already fallen in love with the idea of owning the stock.