Which one of the following statements is correct?

1. If a stock is currently undervalued by the market, marginal investors will sell the stock.

2. If a stock is currently overvalued by the market, marginal investors will buy the stock.

3. If a stock is currently undervalued by the market, its expected return will increase as its price rises.

4. If a stock is currently overvalued by the market, its expected return will increase as its price drops.