Many people prefer tried-and-tested, low-risk investment options because these offer protection in the face of economic uncertainties. Index funds are among such investment options, and quite a few of them end up performing better than other types of mutual funds. Vanguard, a giant in the investment management industry, offers a host of index funds that strike the right balance between risks and returns. Here are some of its best index funds to consider buying today: 1. Vanguard S&P 500 This popular index fund is also called the Vanguard 500 Index Fund (VFIAX), and it tracks and invests in stocks that are a part of the S&P 500 index. Basically, the S&P 500 index tracks the stocks of the top 500 companies that are listed on stock exchanges in the country, so there is a good chance of high returns. Also, investing in this fund diversifies the investor portfolio to a great extent, reducing overall risk. The risk further diminishes with this type of investment because it tracks a highly reputed index in the financial market. The Vanguard S&P 500 lends itself well to long-term investment goals, wherein the plan is to let the corpus grow on its own time before reaping its benefits.