In truth, there is no magic number of investments. However, financial theory and experts provide a framework you can apply to your unique situation based on the amount of risk you want to take. As a good general rule, most successful investors hold 10-20 shares in their portfolios which greatly reduces risk.
Most people might to aim to hold between 10 and 20 stocks. Even those can take a lot of time to manage, though, so consider a low-fee, broad-market index fund, such as one that tracks the Sɪmp;P 500, for much of your money. Learn more by searching for the terms “index fund” and “Motley Fool” using Google.