Final answer:
Portfolio investment is the practice of investing in a diverse portfolio of stocks to reduce risk and increase potential profitability.
Step-by-step explanation:
Portfolio investment refers to investing in a diverse portfolio of stocks. It involves buying stocks or bonds from a wide range of companies instead of investing in a single company's stock or bonds. The purpose of portfolio investment is to reduce risk through diversification. By spreading investments across multiple companies, any losses from one investment are offset by gains from others, resulting in a more stable and potentially profitable investment portfolio.