A stock with a current price that is not justified by its earnings outlook or price/earnings (P/E) ratio and, therefore, is expected to drop in price. Overvaluation may result from an emotional buying spurt, which inflates the stock's market price, or from a deterioration in a company's financial strength.

Investors may be willing to pay more for stocks with superior growth potential, but they don't want to overpay for a company with growth prospects that don't justify its current market price. One way to determine whether a stock may be overvalued is to look at the price-to-earnings-to-growth (PEG) ratio. For example, a stock is generally considered to be fairly valued if the PEG ratio is 1 (which means the P/E ratio equals the estimated earnings growth), and possibly overvalued if the PEG is more than 1.