When you think of someone making an investment in the stock market, what do you envision? Perhaps you picture a coworker standing at the water-cooler, mentioning his or her recent stock pick that they're confident will prove to be a winner, or a stockbroker in a suit, waiving and yelling on the crowded and boisterous floor of a stock exchange, trying to lock in a purchase of shares in a specific company the investor thinks is poised for growth. In the modern era of investing however, there are many options for Americans looking to invest in the stock market that take on a much different form than buying individual company stock, such as investments into a fund that contains a basket of underlying stocks or bonds. Employer-sponsored retirement accounts often limit investment options exclusively to these kind of funds. The two most common kinds of funds that investors have access to and can utilize are Exchange-Traded Funds (ETFs) and Mutual Funds.