Here we categorize the sectors of the stock market. There are ten (10) different sectors that you can invest in. You can invest in any of these sectors through funds. These can be either exchange-traded funds (ETFs) tied to a widely recognized index or actively managed mutual funds that try to outperform the stock market sector. Its good to diversify your portfolio with different sectors when investing, in case, for example, Health Care is tanking you have Financials or Technology to balance your portfolio.