What Are Index Funds, and How Do They Work?

Written By
I. Mitic
July 10,2023

If hand-selecting stocks or bonds isn’t your idea of a good time, and you prefer a passive approach to trading, you should consider index funds. We’ll walk you through everything you need to know about these funds, from how they’re created to the benefits they offer.

Index Fund Definition

So, what are index funds? An index fund is a type of mutual fund that tracks a specific market index, such as the Standard & Poor’s 500 Index (S&P 500) or the Dow Jones Industrial Average (DJIA). Index funds are passive investment vehicles, meaning a portfolio manager does not actively manage them. Instead, index funds are managed in a way that tracks the index they are associated with. 

Let’s say you are looking to invest in an index fund. In doing so, you’re investing in all the companies that make up a specific index instead of investing in a single company. Index funds track nearly every major stock and bond market index. This gives investors a lot of flexibility when choosing a fund that best suits their needs.

An index can track almost all financial markets. Some of the most popular index funds are the S&P 500, the DJIA, Bloomberg U.S. Aggregate Bond Index, Nasdaq Composite Index, and MSCI EAFE Index, which tracks foreign stocks.

Index Funds Framework

If you’re still unclear on how index funds work, a good place to start is understanding that they are a type of mutual fund, also called an investment vehicle. They pool money from many investors and invest it by purchasing all or a selection of securities that make up the associated index.

For example, the SPDR S&P 500 ETF Trust (SPY) is an index fund that tracks the S&P 500 Index. This low-cost index fund holds all 500 stocks in the same proportions as they are represented in the index. This gives the SPY fund a similar risk and returns profile to the S&P 500 benchmark index.

It’s worth knowing that fund managers mimic the index by investing in the same stocks and bonds proportionately as the index they track. This is done using a technique called full replication. In some cases, however, a fund manager may not be able to purchase all of the securities in an index. When this happens, they may use an optimizing technique to achieve a similar risk and return profile but with a lower investment.

Once you have learned the ropes, you can start picking the perfect index funds for your portfolio. To determine what are the best index funds to invest in, you should pay attention to the expense ratio, minimum investment requirements, if there are any, and your investment objective. After opening a brokerage account at a reliable online stock broker and buying the shares, you should actively follow up and rebalance your portfolio as needed.

Advantages of Index Funds

Index funds offer several advantages compared to other types of investments, making them one of the most popular ways to invest. Some of the most valued benefits include:

Lower Expenses

Index funds typically have lower expenses than actively managed mutual funds. This is because they are not actively managed and therefore do not require you to pay the same fees. The only thing that fund managers track is the underlying assets, a process that is not as time-consuming nor it requires the same amount of labor and resources.

When learning what index funds are, it’s worth mentioning that the only cost associated with them is the expense ratio; some funds offer zero expense ratios, while others often cost less than one percent.


Index funds offer investors instant diversification. This is because they track a basket of assets, which helps spread out the risk. For example, an index fund that tracks the S&P 500 will have 500 different stocks in its portfolio. Therefore, investing in the S&P 500 gives you instant access to 500 companies. This is much more diversifying than investing in a single stock, which exposes you to the risk of that one company going under or underperforming.


Now that you’re familiar with what index funds are and how they work, you are aware that they represent very simple investments. There is no need to try and pick the best stocks or time the market. All you need to do is invest in an index fund that tracks the asset class you are interested in, and you will have instant exposure to that market. This makes index funds ideal for beginner investors or those who don’t want to actively manage their investments.

Higher Returns 

In the long run, low-cost index funds have outperformed actively managed funds. This is because it is very difficult for fund managers to beat the stock market. In fact, studies have shown that the vast majority of fund managers underperform the market. Investing in index funds makes you likely to earn higher returns than if you had invested in actively managed funds. 

As passively managed funds do not attempt to beat the market but try to match its overall risk and return characteristics, they carry lower risks and allow for higher returns. Index funds are an excellent choice for those who want to invest their money and forget they did so until the time comes to reap the benefits. They are generally considered a great portfolio for retirement accounts.

Bottom Line

Let’s sum up what index funds are. They are a type of mutual fund that track a basket of assets, which helps spread out the risk. Index funds have the potential to generate higher returns than actively managed mutual funds over the long term. 

If you’re a beginner investor or don’t want to manage your investments actively, index funds may be the right choice. Also, because these funds are passively managed, they have a lower chance of underperforming the market. Finally, index fund fees are generally lower than actively managed mutual fund fees.


What Is an Index Fund, and How Does It Work?


An index fund is a type of mutual fund with a portfolio that tracks the performance of a specific market index, such as the Standard & Poor’s 500 Index. Index funds are passive investment vehicles that aim to track the performance of a given market index rather than outperform it. 

Are Index Funds a Good Investment?


Now that you know what index funds are and are aware of some of the benefits they offer, you may be wondering if index funds are a good investment. The answer to this question depends on your investment goals and objectives. If your goal is to simply track the performance of a particular market index, then index funds may be a good investment for you. However, if your goal is to outperform the market in a short period, then index funds may not be the best option for you. 

Are Index Funds Good for Beginners?


Index funds can be a good investment for beginners because they are relatively simple to understand and manage. Additionally, index funds offer the potential for diversification and long-term growth. If you’re a beginner investor and want to learn what index funds are and how to invest in them, you should give our guide a read. 

About author

For years, the clients I worked for were banks. That gave me an insider’s view of how banks and other institutions create financial products and services. Then I entered the world of journalism. Fortunly is the result of our fantastic team’s hard work. I use the knowledge I acquired as a bank copywriter to create valuable content that will help you make the best possible financial decisions.

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